Block 7 Repro Kalli Questions Prt 3

In the absence of fertilization, the corpus luteum degenerates and forms scar tissue called the corpus albicans. This is because the corpus luteum is a temporary structure that forms in the ovary after ovulation and is responsible for producing hormones, such as progesterone, which are necessary for maintaining the uterine lining for potential implantation of a fertilized egg. If fertilization does not occur, the corpus luteum is no longer needed and begins to degenerate, eventually forming scar tissue. This process marks the end of the menstrual cycle and prepares the body for the next ovulation.

During fertilization, enzymes released from the cortical granules cause the oocyte plasma membrane and the zona pellucida to undergo a conformational change. This change prevents additional sperm from penetrating the oocyte, ensuring that only one sperm can fertilize the egg. This process is known as the cortical reaction and is an essential step in preventing polyspermy, where multiple sperm fertilize the same egg.

The surge of luteinizing hormone (LH) initiated by high estrogen levels causes the oocyte of a mature Graafian follicle to complete the 1st meiotic division just prior to ovulation. LH surge is a crucial event in the menstrual cycle that triggers ovulation. High levels of estrogen produced by the maturing follicles stimulate the release of LH from the anterior pituitary gland. LH surge then induces the completion of the 1st meiotic division in the oocyte, leading to the release of a mature egg from the ovary.

A multilaminar primary follicle is characterized by a primary oocyte surrounded by many layers of follicular or granulosa cells. This description indicates that the follicle is in an early stage of development, with multiple layers of cells surrounding the oocyte. This is different from the other options, which describe different stages of follicle development or different types of cells surrounding the oocyte.

Estrogens from the granulosa cells stimulate proliferation and regeneration of the endometrial lining. Estrogens are produced by the granulosa cells in the growing follicles of the ovaries. These estrogens play a crucial role in preparing the uterus for implantation and pregnancy. They stimulate the growth and development of the endometrial lining, making it thick and rich in blood vessels. This prepares the uterus to support the implantation of a fertilized egg. Estrogens also promote the proliferation of endometrial cells, ensuring that the lining is ready for potential implantation.

The correct answer is that the cortical granules release enzymes that alter the oocyte plasma membrane and the zone pellucida thus preventing polyspermy. During fertilization, the cortical granules in the oocyte release enzymes that cause a reaction in the oocyte plasma membrane and the zone pellucida. This reaction creates a barrier that prevents additional sperm from penetrating the oocyte, ensuring that only one sperm can fertilize the egg. This process is known as the cortical reaction and is essential for preventing polyspermy, which is the fertilization of an egg by multiple sperm.

The correct answer is that the follicular cells of primordial follicles secrete oocyte maturation inhibitor (OMI) that stops the development of the primary oocyte. This statement is correct because the follicular cells surrounding the oocyte in the primordial follicle release oocyte maturation inhibitor, which prevents the oocyte from maturing until it is ready for ovulation. This inhibitor helps regulate the timing of oocyte maturation and ensures that it occurs at the appropriate time for fertilization.

Estrogen is the hormone that influences the endometrial lining of the uterus during the proliferation phase of the menstrual cycle. This hormone is responsible for thickening the endometrium, preparing it for potential implantation of a fertilized egg. Estrogen also promotes the growth of blood vessels in the endometrium, ensuring a rich blood supply to support the potential pregnancy. Additionally, estrogen stimulates the production of cervical mucus, which aids in the transport of sperm through the cervix and into the uterus.

The primordial follicles are the earliest stage of follicular development in the ovaries. They consist of a primary oocyte, which is an immature egg cell, surrounded by a single layer of squamous follicular cells. This description best suits the characteristics of primordial follicles.

The correct answer is "Follicle stimulating hormone stimulates the granulosa layer to convert androstenedione to estrogen." This statement accurately describes the role of follicle stimulating hormone (FSH) in the maturation of the graafian follicle. FSH acts on the granulosa cells within the follicle, stimulating them to convert androstenedione, a precursor hormone, into estrogen. This process is crucial for the development and maturation of the follicle, ultimately leading to ovulation.

The statement that follicular cells of the primordial follicles secrete oocyte maturation inhibitor is correct. This inhibitor prevents the oocyte from undergoing further maturation until it is stimulated by hormones during the menstrual cycle. The other statements are incorrect. Primary oocytes are arrested in the diplotene stage of prophase I before birth, primary follicles continue to form after birth, primary spermatocytes are formed after birth, and ova are not produced at the time of birth.

Acrosin and neuraminidase are enzymes that are released from the acrosome, which is a structure located at the tip of the sperm. These enzymes are responsible for digesting the zona pellucida, which is a protective layer surrounding the egg. This allows the sperm to penetrate the zona pellucida and fertilize the egg. The other options mentioned in the question, such as the release of enzymes from cortical granules or the dropping off of the sperm's tail, are not accurate explanations of the fertilization process.

Progesterone secreted from the corpus luteum inhibits the secretion of luteinizing hormone. This is because progesterone plays a role in maintaining the uterine lining and preparing it for implantation of a fertilized egg. Inhibiting the secretion of luteinizing hormone helps to prevent further ovulation and allows the uterine lining to be maintained for a potential pregnancy.

During prophase I of meiosis I, homologous chromosomes pair up and form a structure called a tetrad. This allows for the exchange of genetic material between the homologous chromosomes, a process known as crossing over. This exchange of genetic material increases genetic diversity. Therefore, the statement that pairing of homologous chromosomes occurs in prophase I of meiosis I is correct.

Luteinizing hormone stimulates the granulosa and theca interna layers to form the corpus luteum. During the menstrual cycle, the corpus luteum is formed after ovulation occurs. The granulosa and theca interna layers of the ruptured follicle transform into the corpus luteum under the influence of luteinizing hormone. The corpus luteum then secretes hormones such as progesterone, which is important for preparing the uterus for potential implantation of a fertilized egg. This process is essential for the regulation of the menstrual cycle and the maintenance of pregnancy if fertilization occurs.

Secondary spermatocytes have 2n DNA, meaning they have a diploid number of chromosomes. This is because they undergo meiosis I, which reduces the chromosome number by half. Therefore, secondary spermatocytes have 2n DNA and are haploid, containing half the number of chromosomes as the parent cell.

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