Histologi Sistem Reproduksi Wanita (video kedua dari 4 video)-Ovarium

Summary

This video delves into the histology of the ovary, explaining its structure and dynamics. The ovary consists of the outer tunica albuginea and the inner parenchyma, divided into the cortex and medulla. The cortex contains ovarian follicles, which undergo several stages of development, from primordial to primary, secondary, and mature follicles, culminating in ovulation. The hormonal regulation by FSH, LH, estrogen, and progesterone is also highlighted, influencing follicle growth and ovulation. The corpus luteum forms post-ovulation, essential for early pregnancy maintenance. Overall, the video offers an in-depth exploration of ovarian function and its hormonal controls.

Takeaways

• 😀 The ovary is an oval-shaped organ with an outer layer called the Tunica albuginea and an internal area called the parenchyma, which consists of the medulla and cortex.
• 😀 The medulla of the ovary is filled with connective tissue and contains blood vessels, lymphatics, and nerves, while the cortex contains various follicular stages.
• 😀 At birth, a female's ovaries contain approximately 1 million primordial follicles, which reduce to around 500,000 due to follicular atresia.
• 😀 Primordial follicles consist of a primary oocyte surrounded by a single layer of squamous epithelial cells.
• 😀 During puberty, hormonal changes stimulate the growth of primordial follicles, progressing through stages to eventually release the oocyte during ovulation.
• 😀 The growth of an ovarian follicle involves changes in the oocyte and the surrounding epithelium, transitioning from squamous to cuboidal cells, and later forming multiple layers of granulosa cells.
• 😀 As the follicle grows, a new structure called the zona pellucida forms between the oocyte and granulosa cells, which is essential for fertilization.
• 😀 In the secondary follicle stage, fluid-filled spaces (antrum) form between granulosa cells, and the follicle enlarges.
• 😀 The dominant follicle, called the Graafian follicle, continues to grow and may reach a diameter of over 2 cm, preparing for ovulation.
• 😀 After ovulation, the remaining follicular structure forms the corpus luteum, which produces progesterone to support early pregnancy, or degenerates into corpus albicans if fertilization does not occur.

Q & A

What is the structure of the ovary?

The ovary has an oval shape and is covered by a connective tissue layer called the Tunica albuginea. Inside the ovary, there are two parts: the medulla, which consists of connective tissue, blood vessels, lymphatic vessels, and nerves, and the cortex, which contains ovarian follicles.

What are ovarian follicles, and where are they located?

Ovarian follicles are spherical structures located within the cortex of the ovary. They vary in size, and the smaller ones are located near the outer layer, while larger ones are deeper within the cortex.

What are primordial follicles and when do they form?

Primordial follicles are the earliest stage of ovarian follicles, consisting of a primary oocyte surrounded by a single layer of squamous epithelial cells. These follicles form during fetal development, with approximately 1 million formed before birth, though only around 500,000 remain at birth due to atresia.

How does a primordial follicle develop after puberty?

After puberty, hormonal changes, including the secretion of follicle-stimulating hormone (FSH), trigger the growth of a group of primordial follicles. These follicles progress through stages, becoming primary, secondary, and eventually mature follicles.

What changes occur in the follicle during its development?

As the follicle matures, the oocyte increases in size, and the surrounding epithelial cells change from simple squamous to cuboidal. The number of epithelial layers increases as well. Additionally, new structures such as the zona pellucida (a protective layer around the oocyte) and granulosa cells (which surround the oocyte) form.

What is the role of the theca cells in follicle development?

Theca cells, which surround the follicle, play a crucial role in hormone synthesis, particularly estrogen. Theca interna cells produce androgens, which are converted into estrogen by granulosa cells, and theca externa cells contribute to the structural integrity of the follicle.

What is the significance of the zona pellucida?

The zona pellucida is a glycoprotein layer that forms between the oocyte and granulosa cells. It is important for fertilization, as it prevents polyspermy (fertilization by more than one sperm) and plays a role in sperm recognition and binding.

What happens during the secondary follicle stage?

During the secondary follicle stage, the follicle grows larger, and spaces filled with fluid (antrum) form between the granulosa cells. This fluid-filled space coalesces into a single large antrum, which is characteristic of the secondary follicle.

How does a follicle transition into a Graafian follicle?

As the secondary follicle matures, one follicle becomes dominant and enlarges to become the Graafian follicle (also known as the mature or tertiary follicle). It reaches a diameter of over 2 cm, and the antrum becomes very large, pushing the oocyte to the edge of the follicle.

What hormonal changes occur during ovulation?

Just before ovulation, there is a sharp increase in luteinizing hormone (LH) levels, which triggers the release of the oocyte from the Graafian follicle. Estrogen, produced by granulosa cells, provides negative feedback to the hypothalamus and pituitary to regulate hormone levels.

What happens to the follicle after ovulation?

After ovulation, the ruptured Graafian follicle transforms into a structure called the corpus luteum. The corpus luteum secretes progesterone, which helps maintain the early stages of pregnancy. If fertilization does not occur, the corpus luteum degenerates into the corpus albicans.

What is the role of the corpus luteum in pregnancy?

The corpus luteum plays a critical role in early pregnancy by secreting progesterone, which helps sustain the uterine lining. If fertilization occurs, the developing embryo produces human chorionic gonadotropin (hCG), which signals the corpus luteum to remain active and continue progesterone production.