Flashcards in Repro 4 Male Anatomy Deck (122)
What is the scrotal sac made up of and what does it contain?
Cutaneous sac of skin and superficial fascia (dartos muscle within this) - out pocketing of anterior abdominal wall, developed from labiosacral folds
Contains testes, epididymus and first part of spermatic cord
Why are the testes outside the body?
Optimum temperature for spermatogenesis is below body temperature
What type of tissue are the testes?
Compound tubular gland
What surrounds the testes?
Tunica albuginea - thick fibrous capsule
What is the mediastinum testis?
A network of fibrous connective tissue on the posterior aspect of the testis connecting with the tunica albuginea. Provides a passageway for sperm to enter the duct system
How many lobules are there in each testis and what are they made from?
About 250 pyramid-shaped lobules divided by strong connective tissue septa - the tunica albuginea
What do the lobules in the testes contain?
Between one and four highly convoluted seminiferous tubules
What occurs in the seminiferous tubules?
Spermatogenesis (germ cells)
Androgen (testosterone) production (Sertoli cells)
Describe the histology of the seminiferous tubules.
Lined by complex stratified epithelium - seminiferous epithelium consisting of Sertoli and spermatogenic (germ cells)
Surrounded by a layer of connective tissue with flattened myofibroblasts and an inner basement membrane
Describe the histology of the Sertoli cells.
Fixed to the basement membrane of the seminiferous tubules
The cytoplasm of each cell forms an elaborate system of processes that extend upwards to the luminal surface, surround the spermatogenic cells and fill all the spaces between them. cell boundaries are therefore difficult to see.
Apical region of each cell has complicated recesses into which the heads of sperms appear to be embedded
What are the more numerous cells in the seminiferous tubules?
What is the innervation of the scrotum?
Anterior - Lumbar plexus
Posterior and inferior - sacral plexus
Which spermatogenic cells rest on the basement membrane?
Spermatogonia, the most primitive form of spermatogenic cells. Later stares are located at successively higher levels in the epithelium
What are primary spermatocytes?
Immature spermatid before it has undergone meiosis (2n)
Why are secondary spermatocytes rarely seen in the seminiferous epithelium?
Short half life. Divide rapidly to form spermatids
How do spermatids appear in light microscopy?
Lightly stained nuclei near the lumen of the seminiferous tubule
Why are primary spermatocytes nuclei variable in appearance?
They are at various stages of the first meiotic division?
What are spermatozoa and where are they?
Mature spermatids. Their deeply staining heads appear to be embedded in the cytoplasm of the Sertoli cells and their tails hang into the lumen of the seminiferous tubule
What is spermatogenesis?
The process by which spermatogenic cells undergo cell proliferation and maturation and are transformed over a period of time into spermatozoa. Last around 70 days and involves cellular nuclei and cytoplasmic changes. Early diploid spermatogonia are transformed into haploid spermatozoa
Where are Leydig cells?
Between the seminiferous tubules in loose connective tissue. AKA interstitial cells
Seen in isolated clusters or in rows along small blood vessels
What is the histological appearance of Leydig cells?
Large spherical nuclei (containing small amounts of peripherally located chromatin and one or two prominent nucleoli)
Why do Leydig cells interact with the seminiferous tubules?
They are steroidogenic and the androgens produced (testosterone) are key for spermatogenesis to occur
What is oligozoospermia?
A clinical condition where there is an abnormally low number of spermatozoa in the semen
What is azoospermia?
No sperms appear in the ejaculate
What is cryptorchid testis?
Maldescended testis. Spermatogenesis is impaired because of the elevated temperature. The germ cells are absent while the Sertoli and Leydig cells secrete male sex hormones
Associated with an increased incidence of malignant testicular tumours
What is orchitis?
Inflammation of the testis. Occurs in some individuals who suffer from umps after puberty. Results in impaired spermatogenesis, occasionally leading to seminiferous tubule degeneration or at times infertility
How might an absence of germ cells arise?
May be congenital or acquired e.g. drugs, viral infect, irradiation, cryptorchidism
How common are testicular tumours and from where do they usually arise?
Rare, most arise from germ cells with a high degree of malignancy
What is the arterial supply of the testes?
Direct gonadal branches from the abdominal aorta