Embriologia do sistema reprodutor masculino e feminino. Testículo e ovário

Summary

In this educational video, Professor Verônica discusses the embryology of the reproductive system, breaking it down into multiple episodes. The focus of this session is on the development of male and female gonads, including the formation of testes and ovaries. The gene SRY plays a critical role in testicular development, while its absence leads to ovarian formation. The lecture also covers the process of testicular descent into the scrotum and the development of reproductive organs. The lesson concludes with an introduction to the future exploration of genital duct differentiation.

Takeaways

• 😀 The reproductive system's embryology is introduced, focusing on the formation of male and female gonads (testes and ovaries).
• 😀 Gonads develop from the intermediate mesoderm, which is located between the paraxial and lateral mesoderm during embryogenesis.
• 😀 Gonadal development starts with the formation of the urogenital ridge, which differentiates into gonadal tissue.
• 😀 Germ cells, originating in the yolk sac, migrate through the dorsal mesentery to populate the developing gonads.
• 😀 The sex of the embryo is initially undifferentiated, with sexual differentiation occurring later due to genetic factors, such as the SRY gene on the Y chromosome.
• 😀 The presence of the SRY gene in male embryos triggers the differentiation of gonads into testes, whereas its absence leads to the formation of ovaries in female embryos.
• 😀 The testicles are initially formed within the abdominal cavity but later descend into the scrotum, a process crucial for maintaining an optimal temperature for sperm production.
• 😀 Testicular differentiation involves the formation of seminiferous tubules, Sertoli cells, and Leydig cells, which are responsible for sperm development and testosterone production.
• 😀 Testosterone is key to the development of male genital ducts and external genitalia, as well as the differentiation of the prostate.
• 😀 In females, the absence of testosterone and the lack of the SRY gene allow the Mullerian ducts to remain and differentiate into female reproductive organs such as the uterus and fallopian tubes.
• 😀 Ovarian development occurs with the formation of cortical cords, which later degenerate, and secondary cords that contribute to the formation of ovarian follicles.
• 😀 The descent of the ovaries is much less significant than the descent of the testicles and involves the formation of a ligament that anchors the ovaries to the pelvic region.

Q & A

What is the main focus of the lesson in the transcript?

The lesson focuses on the embryology of the reproductive system, specifically the formation of the male and female gonads (testes and ovaries).

What are the two primary embryonic layers involved in the formation of the gonads?

The gonads are formed from the mesoderm, specifically the intermediate mesoderm, which is located between the paraxial and lateral mesoderm layers.

What is the significance of the gene SRY in the development of the gonads?

The SRY gene, located on the short arm of the Y chromosome, is responsible for determining whether the gonads will develop into testes (in male embryos). In the absence of the SRY gene, the gonads will develop into ovaries (in female embryos).

How do the testes form during embryonic development?

The testes form from the gonadal ridge, where mesothelial cells proliferate and form primary sex cords that penetrate into the underlying mesenchyme. Germ cells migrate from the yolk sac to incorporate into these cords, ultimately forming seminiferous tubules.

What role do Sertoli cells play in the development of the testes?

Sertoli cells, which are derived from the mesothelial cells of the gonadal ridge, play a crucial role in supporting germ cells and in producing anti-Müllerian hormone (AMH), which causes the degeneration of the Müllerian ducts, preventing the development of female reproductive structures.

What is the function of testosterone during fetal development in male embryos?

Testosterone, produced by Leydig cells around the seminiferous tubules, is essential for the development of male genital ducts and the formation of external male genitalia, as well as the differentiation of the prostate.

Why do the testes need to descend into the scrotum during development?

The testes must descend into the scrotum because the scrotal environment provides a cooler temperature, which is necessary for the proper development and function of sperm cells. The internal body temperature is too high for sperm production.

What is the process that guides the descent of the testes into the scrotum?

The testes are initially located in the abdominal cavity but descend through the inguinal canal into the scrotum. This process is assisted by the gubernaculum, a fibrous structure, and the processus vaginalis, a peritoneal extension that guides the testes during descent.

What are the key differences in the formation of the ovaries compared to the testes?

Unlike the testes, the formation of ovaries does not require the presence of the SRY gene. In the absence of SRY, the gonads develop into ovaries. The ovarian development involves the formation of primary sex cords that undergo degeneration, with secondary sex cords forming follicles around the primordial germ cells.

What are the two regions of the ovary and their functions?

The ovary has a medullary region, which is composed of connective tissue and blood vessels, and a cortical region, which contains ovarian follicles. The cortical region is functional, where the follicles are involved in oocyte maturation and hormone production.