Review Question - QID 216759

This patient has undergone a testicular biopsy for infertility testing. The figure’s labeled cells are Sertoli cells, which are responsible for inhibin production as well spermatogenesis.

Sertoli cells line the seminiferous tubules, supporting sperm cell development. They secrete many key substances that promote spermatogenesis, including anti-Müllerian hormone, androgen-binding protein, inhibin, and activin. Sertoli cells also play an important structural role in maintaining the blood-testis barrier, which separates the lumen of the seminiferous tubule from interstitial blood, preventing autoimmune reactions against germ cells. This is achieved by tight junctions between adjacent Sertoli cells. Lastly, Sertoli cells also have phagocytic function through consuming resultant excess cytoplasm from spermatogenesis. Histologically, they have characteristic dark nucleoli.

Peterson and Söder review the functions and reproductive health implications of Sertoli cells. While the many proteins expressed by Sertoli cells have been identified, understanding of their specific roles in spermatogenesis is still limited. Fertility is critically influenced by the number of Sertoli cells, which stop mitotic activity at puberty. It has been shown that testicular size and sperm output are correlated with Sertoli cell numbers. Impaired Sertoli cell differentiation is thus linked to low sperm count and testicular cancers.

Figure A is a micrograph of seminiferous tubules with Sertoli cells (highlighted by the black squares).

Incorrect Answers:
Answer 1: Androstenedione secretion is a function of theca cells. Theca cells are found in ovarian follicles and play a role in folliculogenesis. The secreted androstenedione is converted into 17β estradiol by granulosa cells using aromatase.

Answer 3: Luteinizing hormone production is a function of the anterior pituitary. The pituitary gland is an important endocrine structure composed of an anterior and posterior portion. The anterior pituitary has somatotrophs, corticotropes, thyrotropes, gonadotrophs, and lactotrophs that synthesize and produce growth hormone, adrenocorticotropin, thyroid stimulating hormone, luteinizing/follicle stimulating hormones, and prolactin, respectively. The posterior pituitary secretes oxytocin and vasopressin that are initially produced in the hypothalamus.

Answer 4: Testosterone production is a function of Leydig cells. They are found near the seminiferous tubules in the testicle. Similar to theca cells, Leydig cells increase androgen production stimulated by luteinizing hormone.

Answer 5: Transport of spermatozoa is a function of peritubular myoid cells. These cells make up the smooth muscles that surround the seminiferous tubules. While mechanisms are not totally understood, other functions include structural support and spermatogenesis regulation with Sertoli cells.

Bullet Summary:
Sertoli cells play an important role in spermatogenesis, which includes inhibin production.