BGDA Practical - Male Reproductive Tract Histology

Introduction

This current page provides background support information for Medicine phase 1 BGD Histology Practical Virtual Slides. Page does not form part of the BGDA practical class virtual slides.

Moodle Lab Slides - Male Reproductive Tract

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Slides: Female | Male | Placenta

Practical Manual Notes 2013 online PDF (2 pages) | BGDA Practical - Female Reproductive Tract Histology

Historic drawing

Testis histology

Objectives

Gain an overview of the microanatomy of the male reproductive system.
Undertake a microscopical examination of the testis, epididymis, vas deferens, seminal vesicle, prostate gland, penis, and sperm. The functional significance of the various histological structures identified will be discussed.

Links: Testis Development | Prostate Development | Histology

Testis Histology

Convoluted Seminiferous Tubules

tubules are enclosed by a thick basal lamina and surrounded by 3-4 layers of smooth muscle cells (or myoid cells).
tubules are lined with seminiferous epithelium consisting of two cell types: spermatogenic cells and Sertoli cells.

Spermatogonia

first cells of spermatogenesis.
originate in week 4 of fetal development in the endodermal walls of the yolk sac and migrate to the primordium of the testis, where they differentiate into spermatogonia.
Spermatogonia remain dormant until puberty. They are always in contact with the basal lamina of the tubule.
Two types of spermatogonia can be distinguished in the human seminiferous epithelium:

 ** Type A spermatogonia have a rounded nucleus with very fine chromatin grains and one or two nucleoli. They are stem cells which divide to form new generations of both type A and type B spermatogonia.  ** Type B spermatogonia have rounded nuclei with chromatin granules of variable size, which often attach to the nuclear membrane, and one nucleolus. Although type B spermatogonia may divide repeatedly, they do not function as stem cells and their final mitosis always results in the formation of primary spermatocytes.

Primary spermatocytes

lie in the cell layer luminal to the spermatogonia.
appear larger than spermatogonia.
immediately enter the prophase of the first meiotic division, which is prolonged (about 22 days).
large number of primary spermatocytes is always visible in cross-sections through seminiferous tubules.
cell divisions, from the formation of primary spermatocytes and onwards, to the production of the spermatocytes, are incomplete.
cells remain connected by bridges of cytoplasm.
completion of the first meiotic division results in the formation of secondary spermatocytes

Secondary spermatocytes

smaller than primary spermatocytes.
rapidly enter and complete the second meiotic division (seldom seen in histological preparations).
division results in the formation of spermatids.

Spermatids

lie in the luminal part of the seminiferous epithelium.
small cells (about 10 µm in diameter) with an initially very light (often eccentric) nucleus.
- chromatin condenses during the maturation of the spermatids into spermatozoa, and the nucleus becomes smaller and stains darker.
terminal phase of spermatogenesis is called spermiogenesis
- consists of the morphological differentiation of the newly formed spermatids into spermatozoa.

Spermatozoa

This brief animation shows an overview of the structural components of the spermatozoa.

Blue - Nucleus containing male haploid genome required to combine with oocyte haploid genome to form diploid zygote.
Red - Acrosome containing enzymes required to digest the zona pellucida. The acrosome develops as a highly modified golgi structure.
Green - Centriole and axonema required for spermatozoa movement.
Orange - Mitochondria and annulus required for energy for spermatozoa movement.
Grey - Cytoplasm and plasmolemma, cell membrane containing membrane proteins for chemotaxis and binding to the oocyte zone pellucida.

mature human spermatozoon is about 60 µm long and actively motile.
divided into head, neck and tail.
- head - (flattened, about 5 µm long and 3 µm wide) chiefly consists of the nucleus (greatly condensed chromatin!). The anterior 2/3 of the nucleus is covered by the acrosome, which contains enzymes important in the process of fertilisation. The posterior parts of the nuclear membrane forms the so-called basal plate.
- neck - short (about 1 µm) and attached to the basal plate. A transversely oriented centriole is located immediately behind the basal plate. The neck also contains nine segmented columns of fibrous material, which continue as the outer dense fibres into the tail. 
- tail - further divided into a middle piece, a principal piece and an end piece. The axonema (arrangement of microtubules in all cilia) begins in the middle piece. It is surrounded by nine outer dense fibres, which are not found in other cilia. In the middle piece (about 5 µm long), the axonema and dense fibres are surrounded by a sheath of mitochondria. The middle piece is terminated by a dense ring, the annulus. The principal piece is about 45 µm long. It contains a fibrous sheath, which consists of dorsal and ventral longitudinal columns interconnected by regularly spaced circumferential hoops. The fibrous sheath and the dense fibres do not extend to the tip of the tail. Along the last part (5 µm) of the tail, called the end piece, the axonema is only surrounded by a small amount of cytoplasm and the plasma membrane.

<html5media height="240" width="300">File:Spermatozoa_animation.mp4</html5media>

Click Here to play on mobile device

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Epididymis Histology

Pseudostratified Epithelium Nuclei of the epithelial cells are typically located in the widest part of the cell. the nuclei of cells that do or do not reach the surface of the epithelium are often located at different heights within the epithelium, giving the epithelium a "stratified" appearance. The epithelium though is not stratified, therefore named "pseudostratified".

Human Testis (adult)

overview x2
convoluted seminiferous tubules x10
convoluted seminiferous tubules x20
convoluted seminiferous tubules x40
convoluted seminiferous tubules x40
epididymis overview x4
epididymis x10
epididymis x20
epididymis x40
ductus deferens overview x2
ductus deferens x10
ductus deferens x40

Human Testis (young)

overview Loupe
convoluted seminiferous tubules x10
convoluted seminiferous tubules x40
convoluted seminiferous tubules x40
tunica albuginea x20

Other Species

Rabbit

convoluted seminiferous tubules x20
convoluted seminiferous tubules x100

Mouse

postnatal epididymis
14 days postnatal
33 days postnatal
45 days postnatal
2 months postnatal

Ductus Deferens Histology

Prostate Histology


Human prostate histology	Corpora Amylacea	Submucosal gland
(adult, low power overview)	(adult, detail)	(adult, high power detail)

Penis Histology

Terms

cortex - (Latin = rind, or bark) outer layer of an organ.
hilum - or hilus (Latin,= a trifle; depression in a seed) a depression at vascular entrance/exit of a gland or organ.
medulla - (Latin, medulla = pith, marrow) the inner portion of an organ, in contrast to cortex.
mucosa - (Latin, = mucous membrane) thin layer which lines body cavities and passages formed by epithelium and lamina propria.
parenchyma - (Greek," + enkeim = to pour in) the essential functional cells of an organ as opposed to its stroma.
serosa - (Latin, serum = whey; a pale fluid) a serous membrane lining body cavities.
stroma - (Greek, = a cover, table-cloth, bedding) term for the internal supporting frame-work of a tissue, or organ, as opposed to its parenchyma.
tunica albuginea - a dense, white, fibrous sheath enclosing a part or organ.

Links: Female | Ovary | Oocyte | Uterus | Vagina

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Glossary Links

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Cite this page: Hill, M.A. (2023, December 11) Embryology BGDA Practical - Male Reproductive Tract Histology. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/BGDA_Practical_-_Male_Reproductive_Tract_Histology

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