L1

• Fertilization is the process by which male and female gametes fuse.
• Cortical and zona reactions are part of the process of fertilization.
• Resumption of 2nd meiotic division is a part of the process of fertilization.
• Metabolic activation of the egg is a part of the process of fertilization.
• Completion of 2nd meiotic division of female gamete is a part of the process of fertilization.
• Restoration of the diploid number of chromosomes is a part of the process of fertilization.
• Determination of the sex of the new individual is a part of the process of fertilization.
• Initiation of cleavage is a part of the process of fertilization.
• Variation of human species is a part of the process of fertilization.
• Cleavage is the repeated mitotic division of the zygote into smaller units to form blastomeres.
• 90% of births result in death within the first month.
• 5% of births result in survival beyond 1 year.
• Features of these births include intellectual disability, holoprosencephaly, congenital cardiac defects, deafness, cleft lip and palate, eye defect, microphthalmia, anopthalmia, coloboma, XXY (Klinefelter Syndrome), XO (Turner Syndrome), and others.
• The incidence of births with these features is 1 in 500.
• Features of births with these features include being male, sterile, testicular atrophy, gynaecomastia.
• Structural chromosome abnormalities result from chromosome breakage, partial deletion, and short arm of chromosome 5 (Cri-du-chat syndrome), microdeletion, long arm chromosome 15 (Angelman syndrome), maternal chromosome (Prader-Willi syndrome), and deletion of 22q11 (22q11 syndrome).
• Fragile sites and CGG repeats on long arm of X chromosomes are associated with Fragile X syndrome.
• Female gametogenesis occurs prior to fertilization.
• Ovulation is a process that sheds off the ovum from the ovary.
• The ovum has a specific structure.
• Male gametogenesis involves the production of sperm.
• Ejaculation is the process of expulsion of sperm from the male reproductive organ.
• Capacitation is a process where the glycoprotein coat and seminal plasma protein covering the membrane of sperm are removed.
• Fertilization involves the fusion of male and female gametes to form a zygote.
• The location of fertilization is the ampullary region of the uterine tube.
• The phases of fertilization include penetration of the corona radiata, penetration of the zona pellucida, acrosome reaction, cortical reaction, zona reaction, and resumption of the second meiotic division.
• Penetration of the corona radiata involves capacitated sperm passing freely through corona cells, with only one sperm fertilizing the egg.
• Penetration of the zona pellucida involves the zona, a glycoprotein shell surrounding the egg, facilitating and maintaining sperm binding, inducing acrosome reaction, and allowing sperm to penetrate the zona to come into contact with the membrane of the oocyte.
• The release of lysosomal enzyme from cortical granules is part of the zona reaction.
• Permeability of the zona changes during fertilization.
• Fusion of the oocyte and sperm cell membranes involves adhesion of sperm to the oocyte, fusing the plasma membrane, and having the head and tail of the sperm enter the cytoplasm of the oocyte.
• The results of fertilization include cleavage and blastocyst formation.
• Blastocyst formation begins just after fertilization and continues as the zygote passes through the uterine tube, resulting in a rapid increase in the number of cells known as blastomeres.
• Cells become smaller with each division, reaching the 16 cell stage, known as morula.
• At the 16 cell stage, cells arrange in two groups: the inner cell mass, known as embryoblast, and the outer cell mass, known as trophoblast.
• Blastocyst is a thin-walled hollow structure in the early embryonic period containing the inner cell mass and outer cell mass.
• The process of blastocyst formation begins with the morula entering the uterine cavity, followed by endometrial fluid penetrating the zona pellucida, and ends with the blastocyst being ready for implantation.
• Implantation is the process of the blastocyst adhering to the wall of the uterus.
• The uterus at the time of implantation is in the secretory phase, with uterine glands and arteries coiled.
• The endometrium has three distinct layers: the superficial compact layer, the intermediate spongy layer, and the thin basal layer.