Female reproductive toxicology of cadmium

The aim of this study was to determine effects of Cd on the structure of ovary, oviduct and uterus after an experimental administration. Animals were divided into three groups. In group A rabbits received cadmium i.p. and were killed after 48 h. In group C Cd was administered p.o. for 5 month. The group K was the control. Decreased relative volume of growing follicles and increased stroma after Cd administration were detected. The number of atretic follicles was significantly higher after administration of Cd. The most frequent ultrastructural alterations observed were undulation of external nuclear membrane, dilatation of perinuclear cistern and endoplasmic reticulum. In all studied types of cells mitochondria with altered structure were found. In the oviduct the highest amount of epithelium in the group with long-term Cd administration was found. Microscopic analysis showed oedematization of the oviduct tissue, caused by disintegration of the capillary wall. An electron microscopic analysis showed dilatation of perinuclear cistern. The intercellular spaces were enlarged and junctions between cells were affected. Mainly after a long-term cadmium administration nuclear chromatin disintegration was present. In the uterus a significant change was determined in the relative volume of glandular epithelium. Increase of stroma was a sign of uterus oedamatization caused by damage in the wall of blood vessels and subsequent diapedesis. After Cd administration alteration in uterus were less expressed, in comparison with ovary and oviduct. Alteration of nuclear chromatin contain following Cd administration suggests degenerative functional changes.

[The effect of zeranol on muscle structure and the development of the testes in bulls]

The effect was investigated of the Ralgro preparation with the active substance zeranol on histological and histochemical properties of bull muscles. The anabolic effect was displayed by a trend toward greater thickness of muscle fibres in m. longissimus thoracis, m. semitendinosus and m. triceps brachii, whilst differences between the muscles of experimental and control animals were not statistically significant. The bulls administered zeranol had the higher proportions as well as the higher relative volumes of white (aW) muscle fibres, but neither were these differences statistically significant in comparison with the control. The growth and development of testicles are inhibited by zeranol. The inhibition is significant and persists during 30 days after the last administration. Later on, the rate of development and growth are increased with the testicles reaching the weight of the sexual glands of control animals in 90 days after the last administration; the coiled seminiferous tubules grow and spermiogenesis occurs.

[Relation between myoglobin levels and succinate dehydrogenase activity in muscle fibers]

We compared the histochemical activity of succinate dehydrogenase (SDH) and the intensity of reaction to the presence of myoglobin (Mb) in the same muscle fibres m. longissimus thoracis (MLT), m. semimembranosus (MSM), m. rectus femoris (MRF) and caput longum m. tricipitis brachii (MTB). At the same time we also ascertained the myoglobin content of one gram of fresh muscle. We found that the muscle fibre in all the muscles studied in which there is the most intensive reaction in the test for SDH are also the most intensively coloured in the test for Mb. There is also the same relationship in intermediary and white fibres. The reaction in testing for SDH on a cross section is greatest in the subsarcolemmic area. Similar tendencies appear in the distribution of Mb, although they are less marked and only in fibres with intensive reaction. Different muscles have different myoglobin levels. Muscles with a higher proportion of red and intermediary fibres contain more myoglobin than muscles with a high proportion of white fibres. The quantitative values of the levels of Mb (g/fresh muscle) are not, however, proportional to the share of individual types of muscle fibres in the muscles studied.

[The growth of abdominal adipose tissue in various production-type of domestic fowl]

At hatching, the abdominal fatty tissue is less developed than the subcutaneous fatty tissue. However, it grows more intensively during the post-incubation period through both the hyperplasia and hypertrophy of the fat cells. In the cocks, hyperplasia reaches its peak at the age of 9 weeks, followed by a decrease; then hyperplasia continues until the age of 25 weeks. In the hens the peak of hyperplasia comes later, at the age of 14 weeks; then it decreases until the age of 25 weeks is reached. Hyperplasia and hypertrophy are more pronounced in the early period and are somewhat higher in the cocks. During the period of sexual maturation both processes are more intensive in the hens; owing to them, the total weight of the abdominal fatty tissue of hens increases both absolutely and relatively in comparison with the cocks. The cellularity of the first population of adipocytes is assumed to culminate at the age of three to five weeks. Then follows the cellularity of the second population which persists throughout sexual maturation. The pictures of hyperplasia and hypertrophy are qualitatively the same in different production types of fowl, but the size is twice as large in the broiler type than in the laying type of fowl.

[The development and growth of subcutaneous adipose tissue in various production types of domestic fowl]

Hyperplasia and hypertrophy of fat cells of the subcutaneous adipose tissue were studied in different production types of fowl in the post-incubation period. The cocks and hens of laying type were found to have fewer and smaller fat cells than the birds of broiler type. The highest hyperplasia was recorded in the first nine weeks of age, then followed a decrease, lasting until the 25th week. Hypertrophy continued step by step throughout the period of study and increased when hyperplasia decreased. The differences between sexes increase during sexual maturation: in the hens the hypertrophy of cells increases and hyperplasia does not decrease so quickly as in the cocks. Before sexual maturity, hypertrophy as well as hyperplasia are somewhat higher in the cocks.

[Sexual development and levels of plasma testosterone in the light type of cockerel]

The concentration of testosterone in blood plasma during the ontogenetic development of cockerels was studied in relation to the development of spermatogenic part of gonads. On the basis of the results, sexual development of cockerels can be divided into three stages. The first stage (from hatching to the age of eight to nine weeks) was characterized by a slow increase in gonad weight, by low concentration of plasma testosterone (0.4-2.0 nmol/l) and by the occurrence of spermatogonia in testes. In the course of the second stage (from the age of nine to 16 weeks) a rapid increase in the weight of testes and testosterone concentration was observed. At the end of this stage all phases of spermatogenic cycle were observed in gonads; the testosterone levels averaged to 10 nmol/l. In the course of this stage all cockerels reached sexual maturity; large individual differences in spermatogenesis development were observed. The third stage (16 weeks of age and more) was characterized by an intensive spermatogenesis, further increase in gonad weight and by typical variations of the plasma testosterone levels. The concentration of the circulating testosterone increased before the onset of the final stages of the spermatogenic cycle.

[Muscle fibers of pigs sensitive to halothane and resistant to it]

The histological and histochemical structure of m. longissimus thoracis, m. semimembranosus, m. triceps brachii-caput longum and m. rectus femoris was compared in pigs with a positive and negative reaction to halothane treatment. As found, the pigs affected by the malignant hyperthermia syndrome have thicker muscle fibres in the studied muscles. In the course of growth, the muscles of these animals have a larger proportion of red fibres (SO), but it is already at the age of 170 days (weight 100 kg) that light fibres prevail. The relative volume of the FG fibres is larger by 1-5%, as compared with the healthy animals. A higher number of pathologically changed fibres occurs in the pigs sensitive to halothane. The histological picture is individually variable; therefore the histological and histochemical methods cannot be considered as objective in view of MHS diagnosis. The general weakening of the constitution of the pigs is discussed as a possible predisposition factor underlying the development of various health disorders.

[Dystrophic muscular fibers in the muscles of certain breeds of birds]

The occurrence of pathologically changed muscular fibers in some wild species of birds and in economically important domesticated species of birds is described. The hydrops of muscular fibers, necrosis and atrophy with connective tissue infiltration in muscular bundles were detected in breast and thigh muscles in wild birds, e. g. in raven, pigeon and pheasant. The same pathological processes were also found in domesticated species, e. g. in guinea fowl, less often in geese and duck. Their incidence in turkeys and laying types of fowl was more frequent, they were observed most often in muscles of broiler hens. Fission of muscular fibers, very thin, but also hypertrophic fibers and resorption of necrotic fibers were detected in hens besides the above changes. The described histological picture is confronted with the picture of hereditary myodystrophy in chickens.

[Atresia of the follicle during ovarian growth in domestic poultry]

Follicle atresia in the ovary of fowl is apparent as early as the first day of post-incubation development, and affects the primary oocytes. During follicle growth and ripening its intensity increases in such a way that in the laying period up to 20% of follicles are affected. In the course of atresia of primary follicles cells undergo lysis after primary necrotic changes and the surrounding connective tissue overgrows them so that they are obliterated. The growing smaller follicles are mainly affected by obliterative atresia, only sometimes a cyst is temporarily formed. The larger and large follicles are subjected either to obliterative or cystic atresia, either without luteinisation or with luteinisation of cells of membrana granulosa, theca interna or with luteinisation of both membranes. With the follicles up to 500 to 600 microns prevail obliterative forms, with larger follicles cystic forms.

[Submicroscopic changes in the glandular epithelium of the endometrium in cows during the estrous cycle]

During the sexual cycle the structural changes in the cells of the glandular epithelium in the endometrium of a cow are more pronounced than those in the luminal epithelium. Microvilli appear on cell surface during pro-oestrus; in later stages the microvilli disappear and the apical parts penetrate into the lumen. The relative volume of mitochondria increases from pro-oestrus to culminate in oestrus and metoestrus and to drop in dioestrus. The values of the volume and surface area of granular endoplasmic reticulum are also at their highest level in oestrus and metoestrus. The lowest volume and surface area of smooth membranes are recorded in dioestrus, then it markedly increases to culminate in metoestrus. The incidence of lysosomes is variable and their volume culminates in metoestrus. The proliferation of the glandular epithelium has the highest intensity in oestrus and reaches its peak values in metoestrus when the apical parts of cytoplasm contain the largest amounts of smooth-walled vesicles and vacuoles, partly also secretory granules, and when the signs of secretion are observed.

[Submicroscopic changes in the luminal cells of the endometrium in cows during the estrus cycle]

The structure of luminal epithelium cells in the endometrium of a cow shows little variation during the sexual cycle. Various coarse and irregular microvilli are produced on the surface of cells in pro-oestrus and oestrus. Starting from pro-oestrus, the relative volume of mitochondria increases to culminate in met-oestrus and di-oestrus. Their highest number was observed in oestrus; in met-oestrus they enlarge and many of them gradually disintegrate during di-oestrus. The maximum development of granular endoplasmic reticulum was observed in oestrus. The quantitative proportion of smooth membranes is small and their volume and surface area increase from the lowest values in di-oestrus up to culmination in oestrus. The highest number of lysosomes was observed at the end of sexual cycle and in pro-oestrus. In oestrus and met-oestrus the apical parts of cytoplasm contain many smooth-walled vesicles and cisterns.

[Microscopic structure of the uterine mucosa in cows during the estrus cycle]

The endometrium of a cow shows little variation during the sexual cycle. Proliferation starts by increasing the relative volume of the connective-tissue layer of mucous membrane at the onset of pro-oestrus and culminates during oestrus. The volume of luminal epithelium increases more slowly from the lowest values in di-oestrus, the maximum level being obtained in met-oestrus. The volume of glandular epithelium is greatest in met-oestrus and at the start of di-oestrus; during pro-oestrus it is low but increases rapidly afterwards. The nuclei of luminal and gland cells are located basally and are shifted towards the centre of cells in the period of secretory activity. The nucleocytoplasmic ratio of epithelium cells is at its maximum during pro-oestrus and decreases in the subsequent stages. The intensity of PAS reaction also increases at the onset of pro-oestrus, the maximum being obtained in met-oestrus, to persist also in di-oestrus in some cells. Lipid droplets occur, on a larger scale, in gland cells, and the frequency of their occurrence increases in met-oestrus and di-oestrus.

[Microscopic structure of the epithelium of the oviducts in cows during the estrus cycle]

The mucous membrane of a cow is covered with ciliary and secretory cells. The so-called basal cells occur at the basal membrane. The counts of ciliary cells vary during the sexual cycle: they reach the maximum (up to 68%) during oestrus. About 13% of cells lose cilia during metoestrus and at the beginning of dioestrus. Reciliation occurs during pro-oestrus. Light and dark ciliary cells can be discerned by the staining of cytoplasm and by the density of nuclei. A higher variability was found in the secretory cells. There are light and dark cells, cells with a wedge shape and rod-shaped cells. Their frequency and function are discussed. Mitoses of epithelium were found in rare cases. The relative volume of epithelium and the mucous membrane of connective tissues change during the sexual cycle. The volume of secretory cells increases during metoestrus and dioestrus and the volume of ciliary cells increases during pro-oestrus and heat. The volume of nuclei decreases in metoestrus and mainly in dioestrus. PAS positive granules occur in the cytoplasm of secretory cells, mainly during metoestrus, in the apical regions. Ptyalin-resistant polysaccharides, besides glycogen, were detected in the cells. The occurrence rate of lipids varies just slightly during the oestrous cycle.

[Submicroscopic changes in ciliated cells of the epithelium of the oviduct in cows during the estrus cycle]

The submicroscopic changes in the ciliary cells of the ampullar part of oviduct are of qualitative as well as quantitative nature. The mitochondria are mainly located in the supranuclear region. They are small, having densely arranged lamelliform cristae and dense matrix. They have the largest volume in metoestrus and the highest number and the largest surface already during oestrus. The volume and surface of granular endoplasmic reticulum culminates already during pro-oestrus. The reticulum occurs mainly over the nucleus where it produces tubuli densely covered with ribosomes which begin to dilate already during pro-oestrus. The Golgi apparatus and the membranes of smooth reticulum are poorly developed and their quantitative changes during the cycle are not significant. Various forms of lysosomes, whose volume reaches its maximum in dioestrus and during pro-oestrus, constitute a constant component of cytoplasm. Secretory granules occur only rarely in these cells. Kinocilia grow from the basal corpuscles and are more frequent on cells with a light cytoplasm. Higher-density cells have more micro-villi between kinocilia. Deciliation with the disintegration of membrane, filaments and often also the basal corpuscles is observed during metoestrus and at the beginning of dioestrus. Reciliation begins with the formation of basal corpuscles and their replication at the end of dioestrus and in pro-oestrus. The frequency of ciliary regeneration is comparatively small.