Methods for studying human organogenesis

Morphological Peculiarities of Parasitic (Trichosomoides crassicauda) Infection in Rat Urinary Bladder

Trichosomoides crassicauda (T. crassicauda) is a parasite commonly localized in the urinary bladder (UB) of laboratory and wild rats. The presence of these helminths can influence the prediction of pathological changes in the UB. Therefore, the purpose of this research was to make a comprehensive study of the features of the morphological changes in the UB wall of white laboratory rats as a result of T. crassicauda infestation. The study was performed on male rats using histological (Hematoxyline-Eosin and Alcian Blue staining) and immunohistochemical (Ki-67, Hsp70, Hsp90α, CD3 and CD20) methods. T. crassicauda was detected in both urine and UB samples. Morphological changes were observed as disruption in urothelial cell stratification and insignificant proliferative and immune responses in the UB. Increased heat shock protein levels were observed which may suggest a natural body’s resistance to this parasite.

Steroidogenesis during prenatal testicular development in Spix's cavy Galea spixii

Spix's cavy is a potentially good experimental model for research on reproductive biology and sexual development. The aim of the present study was to evaluate the ontogeny of the steroidogenic enzymes involved in testicular androgen synthesis during prenatal development. Testes were investigated on Days 25, 30, 40 and >50 of gestation. Immunohistochemistry and immunoblotting were used to establish the site and relative amount of androgenic enzymes, including 5α-reductase, cytosolic 17β-hydroxysteroid dehydrogenase (17β-HSDI) and mitochondrial microsomal 3β-hydroxysteroid dehydrogenase (3β-HSDII), throughout prenatal development. The testicular parenchyma began to organise on Day 25 of gestation, with the development of recognisable testicular cords. The mesonephros was established after Day 25 of gestation and the ducts differentiated to form the epididymis, as testicular cords were beginning to proliferate and the interstitium to organise by Day 30 of gestation, continuing thereafter. The androgen-synthesising enzymes 5α-reductase, 17β-HSDI and 3β-HSDII were evident in Leydig cells as they differentiated at all subsequent gestational ages studied. In addition, immunoblotting showed an increase in immunoreactivity for the enzymes at Days 30 and 40 of gestation (P<0.05) and a decrease at Day 50 of gestation (P<0.05). It is concluded that the increase in androgenic enzymes in Leydig cells coincides with the functional differentiation of the testes, and with the stabilisation and differentiation of mesonephric ducts forming the epididymis.

Imaging the developing human external and internal urogenital organs with light sheet fluorescence microscopy

Technological advances in three-dimensional (3D) reconstruction techniques have previously enabled paradigm shifts in our understanding of human embryonic and fetal development. Light sheet fluorescence microscopy (LSFM) is a recently-developed technique that uses thin planes of light to optically section whole-mount cleared and immunolabeled biologic specimens. The advent of commercially-available light sheet microscopes has facilitated a new generation of research into protein localization and tissue dynamics at extremely high resolution. Our group has applied LSFM to study developing human fetal external genitalia, internal genitalia and kidneys. This review describes LSFM and presents our group's technique for preparing, clearing, immunostaining and imaging human fetal urogenital specimens. We then present light sheet images and videos of each element of the developing human urogenital system. To the extent of our knowledge, the work conducted by our laboratory represents the first description of a method for performing LSFM on the full human urogenital system during the embryonic and fetal periods.

Pediatric Formulations: Knowledge Gaps Limiting the Expedited Preclinical to Clinical Translation in Children

Traditionally, drug discovery and development research have been primarily focused on the mitigation of disease treatment for the general adult population, often overlooking the medical needs of pediatric patients. While remarkable progress toward the discovery of better medicines has been made, the pharmacological differences between children and adults are often neglected as part of the translation process. In fact, until recently, children have been considered therapeutic orphans due to the lack of significant drug discovery, formulation development, and dosage form design specifically tailored for pediatric patients. Perhaps the least understood is the significant physiological changes that occur during the maturation process from birth to adulthood. It requires careful considerations to achieve age-specific-desired therapeutic outcomes with minimal toxicity. This introduces considerable risk into the preclinical and clinical testing of new medicaments, which until recently, was avoided based on the conventional approach where a demonstration of safe and efficacious use in adults over several years potentially would minimize the chance of adverse juvenile responses. However, the lack of appropriate drug products for children has led to off-label use of adult medicines with potential life-threatening adverse reactions and health complications. Recent developments and future considerations regarding pediatric drug discovery and development using a patient-centric approach in the context of ontogenic biopharmaceutical considerations are discussed below.

Three-dimensional imaging of the developing human fetal urogenital-genital tract: Indifferent stage to male and female differentiation

Recent studies in our lab have utilized three imaging techniques to visualize the developing human fetal urogenital tract in three dimensions: optical projection tomography, scanning electron microscopy and lightsheet fluorescence microscopy. We have applied these technologies to examine changes in morphology and differential gene expression in developing human external genital specimens from the ambisexual stage (<9 weeks fetal age) to well-differentiated male and female organs (>13 weeks fetal age). This work outlines the history and function of each of these three imaging modalities, our methods to prepare specimens for each and the novel findings we have produced thus far. We believe the images in this paper of human fetal urogenital organs produced using lightsheet fluorescence microscopy are the first published to date.

Renal Subcapsular xenografing of human fetal external genital tissue - A new model for investigating urethral development

In this paper, we introduce our novel renal subcapsular xenograft model for the study of human penile urethral and clitoral development. We grafted fifteen intact fetal penes and clitorides 8-11 weeks fetal age under the renal capsules of gonadectomized athymic mice. The mice were treated with a subcutaneous pellet of dihydrotestosterone (DHT), diethylstilbestrol (DES) or untreated with hormones. Xenografts were harvested after fourteen days of growth and analyzed via serial histologic sectioning and immunostaining for Ki-67, cytokeratins 6, 7 and 10, uroplakin and the androgen receptor. Non-grafted specimens of similar fetal age were sectioned and immunostained for the same antigenic markers. 14/15 (93.3%) grafts were successfully propagated and harvested. The developing urethral plate, urethral groove, tubular urethra, corporal bodies and preputial lamina were easily identifiable. These structures demonstrated robust cellularity, appropriate architecture and abundant Ki-67 expression. Expression patterns of cytokeratins 6, 7 and 10, uroplakin and the androgen receptor in xenografted specimens demonstrated characteristic male/female differences analogous to non-grafted specimens. DHT treatment reliably produced tubularization of nascent urethral and vestibular structures and male patterns of androgen receptor expression in grafts of both genetic sexes while estrogenic or hormonally absent conditions reliably resulted in a persistent open urethral/vestibular groove and female patterns of androgen receptor expression. This model's success enables further study into causal pathways by which endocrine-disrupting and endocrine-mimicking substances may directly cause disruption of normal human urethral development or hypospadias.