Trivia Quiz On Stages Of Embryo Development

The amniotic cavity appears on the eighth day as a slit-like space between the trophoblast and the embryoblast. The embryoblast refers to the inner cell mass of the blastocyst, which later develops into the embryo. The amniotic cavity is a fluid-filled space that surrounds and protects the developing embryo, providing it with a suitable environment for growth and development.

The secondary oocyte completes the second meiotic division at fertilization. This is because during fertilization, the sperm fuses with the secondary oocyte, triggering the completion of the second meiotic division. This results in the formation of a mature ovum and a polar body. The ovum then combines with the sperm's genetic material to form a zygote, which will develop into an embryo. Therefore, the completion of the second meiotic division occurs at the moment of fertilization.

During fertilization, the sperm releases acrosomal enzymes which break down the zona pellucida. The zona pellucida is a protective layer surrounding the oocyte. The acrosomal enzymes help the sperm penetrate through this layer, allowing it to reach and fuse with the oocyte. This process is essential for successful fertilization to occur.

During the 2nd week of development, the syncytiotrophoblast layer surrounds the lacunae spaces. This layer is responsible for forming the outer layer of the placenta and plays a crucial role in nutrient and waste exchange between the mother and the developing embryo. The lacunae spaces are fluid-filled spaces that form within the syncytiotrophoblast layer. These spaces provide a means for maternal blood to flow and supply nutrients to the developing embryo. By surrounding the lacunae spaces, the syncytiotrophoblast layer ensures proper blood supply and nutrient exchange during this stage of development.

During the 1st and 2nd week of development, the syncytiotrophoblast degrades the endometrium of the uterus. This is an important step in the implantation process, as it allows the blastocyst to establish a connection with the maternal blood supply. The syncytiotrophoblast is a layer of cells that forms on the outer surface of the blastocyst, and it secretes enzymes that break down the endometrial tissue, allowing the blastocyst to burrow into the uterine lining. This degradation of the endometrium is necessary for successful implantation and subsequent development of the embryo.

A primary follicle is the early stage of follicle development in the ovary. It contains a primary oocyte, which is the immature egg cell, and is surrounded by a single layer of cuboidal follicular cells. As the follicle matures, it will develop into a secondary follicle and eventually an antral follicle, which will have a large antral cavity. Therefore, the correct statement is that a primary follicle contains a primary oocyte and is surrounded by a single layer of cuboidal follicular cells.

When a sperm with 23 chromosomes, including a Y chromosome, fertilizes an oocyte, it results in a male embryo. The presence of the Y chromosome determines the development of male characteristics.

The oocytes are cultured in nutrient medium until they reach the normal second stage of meiotic arrest. Meiotic arrest occurs at the metaphase stage of oocyte development. Therefore, fertilization is carried out at the metaphase of the secondary oocyte.

Progesterone is the correct answer because during the reproductive cycle, progesterone is responsible for enhancing the glandular secretion of the endometrium. This hormone prepares the endometrium for implantation by thickening and enriching it with nutrients, making it a suitable environment for the fertilized egg to implant and develop. FSH (follicle-stimulating hormone) and LH (luteinizing hormone) are involved in the regulation of the menstrual cycle and ovulation, while estrogen and testosterone play roles in various aspects of reproductive function but do not specifically enhance glandular secretion of the endometrium for implantation.

During meiosis I, the amount of DNA is doubled, resulting in 4n DNA. Additionally, the number of chromosomes remains the same as the original diploid number, which is 46 chromosomes. This is because during prophase I of meiosis I, homologous chromosomes pair up and exchange genetic material through a process called crossing over. This results in genetic diversity and ensures that each resulting gamete will have a complete set of chromosomes.

LH, or luteinizing hormone, stimulates the theca interna during the reproductive cycle. The theca interna is a layer of cells surrounding the developing follicle in the ovary. LH triggers the theca cells to produce androgens, such as testosterone, which are then converted into estrogen by the granulosa cells. This estrogen plays a crucial role in the development and maturation of the follicle, leading to ovulation. Therefore, LH is the substance that stimulates the theca interna during the reproductive cycle.

The correct answer is Primordial germ cell. In prepubertal males, the undescended testis is removed due to the higher risk of developing testicular cancer. Histologic analysis reveals that the cells of the germ line in this testis have advanced as far as the primordial germ cell stage of development. This suggests that the testis has not yet undergone further maturation and differentiation into spermatogonia or spermatocytes.

The correct answer is 3 hours before ovulation. The secondary oocyte, or egg cell, is arrested in the metaphase II stage of meiosis, which occurs approximately 3 hours before ovulation. During ovulation, the secondary oocyte is released from the ovary and can be fertilized by a sperm if present. This process is essential for reproduction in females.

The ultrasound examination of the anovulatory patient with PCOS reveals multiple enlarged but immature follicles in her ovaries. This indicates that the oocytes within these follicles have not fully matured. The first stage of meiosis involves the prophase, where the chromosomes condense and pair up. Therefore, the oocytes within these follicles have advanced to the first meiotic prophase.

A secondary follicle is surrounded by the theca interna and theca externa. The theca interna is the inner layer of cells that produce estrogen, while the theca externa is the outer layer of connective tissue. These layers provide support and nourishment to the growing follicle.

The correct answer is Blastomere in her own germ line. This is because polar bodies are produced during oogenesis and are the byproduct of meiosis. The polar bodies do not contribute to the development of the embryo and eventually degenerate. Therefore, the presence of two copies of chromosome 21 in some polar bodies suggests that a nondisjunction event occurred during meiosis in the woman's own germ line, specifically in the blastomere. This means that the woman herself carries the potential risk of passing on the extra copy of chromosome 21 to her offspring.