Spermatogenesis and Oogenesis Overview

The movement of primordial germ cells from the epiblast to the yolk sac and then to the developing gonads.

The process of developing mature eggs from primordial germ cells.

The first stage of oogenesis where primordial germ cells transform into specialized cells called oogonia.

The process of developing mature sperm cells from primordial germ cells through a series of cell divisions and transformations.

The final stage of spermatogenesis where spermatids transform into fully functional sperm cells.

The cells that initiate spermatogenesis: Type A dark, Type A pale, and Type B spermatogonia.

The process where the number of chromosomes is reduced, and cells differentiate during gametogenesis.

The acrosome, located in the head of a sperm cell, contains enzymes that help with fertilization.

A process where cells of the epiblast move through the primitive streak and node, creating a new layer between the epiblast and hypoblast.

The primitive streak is formed on the surface of the ectoderm, acting as a starting point for gastrulation.

The notochord forms from cells migrating from the primitive node and serves as a basis for the development of the axial skeleton.

A temporary connection between the yolk sac and amniotic cavity, involved in forming the digestive system.

The oropharyngeal membrane, which separates the stomodeum (primitive mouth) from the primitive gut, is composed of ectoderm and endoderm.

The cloacal membrane is a temporary structure that separates the hindgut from the outside, eventually forming the anus.

An outpocketing of the yolk sac that extends into the connecting stalk, later becoming obliterated.

The blue color represents the epiblast, viewed from the amniotic cavity side, and the arrow points to the buccopharyngeal/oropharyngeal membrane.

The ectoderm is one of the three primary germ layers in an embryo. It develops into the nervous system, the outer layer of skin (epidermis), and other structures like hair, nails, and teeth.

The endoderm is one of the three primary germ layers in an embryo. It gives rise to the lining of the digestive tract, respiratory system, and other internal organs.

The amniotic sac is a fluid-filled sac that surrounds the developing embryo or fetus. It provides a protective cushion, helps regulate temperature, and allows the fetus to move freely.

The fetal period begins at the 9th week of pregnancy and continues until birth. It is characterized by significant growth and development of the fetus.

The crown-rump length (CRL) is a measurement used to estimate the age of an embryo. It is measured from the top of the head (crown) to the bottom of the buttocks (rump).

The amniotic fluid is a clear, watery fluid that fills the amniotic sac. It helps protect the fetus, regulate temperature, and allows for fetal movement.

The amnion and chorion are two fetal membranes. The amnion encloses the amniotic cavity, while the chorion forms the outer layer and contributes to the placenta.

The yolk sac is a small sac located outside the embryo. It is essential for early development but eventually shrinks as the placenta takes over its functions.

The primitive gut is a blind-ending tube that forms during embryonic development. It's divided into three segments: the foregut, midgut, and hindgut.

The epithelium of the primitive gut originates from the endoderm, a germ layer that gives rise to internal linings of organs.

The stomodeum is the ectodermally lined primitive oral cavity, the initial opening of the mouth.

The proctodeum, the lower part of the anal canal, originates from the ectoderm, the germ layer that forms the outer layer of the body.

The oropharyngeal membrane breaks down before the cloacal membrane. This allows for the connection of the oral cavity to the pharynx and the anal canal to the exterior.

The cloacal membrane appears after the embryo undergoes folding. This folding process is crucial for the formation of the digestive system.

The length of pregnancy is calculated as 280 days or 40 weeks from the start of the last menstrual period.

The length of pregnancy is calculated as 266 days or 38 weeks from fertilization.

By the fifth month of pregnancy, a mother can feel the fetus moving.

The age of the embryo can be determined by measuring the crown-heel length (CHL), which is the distance from the head's top to the foot's sole.

The lanugo hair, a fine hair covering the fetus, develops early and is shed before birth.

The vernix caseosa, a coating protecting the fetus's skin, develops during pregnancy and is shed before birth.

The biparietal diameter of the skull, measured by ultrasound, is used to assess fetal growth.

The external genitalia of a fetus develop sufficiently by the 20th week to be discernible through ultrasound.

The process of blood cell formation, starting with pluripotent hematopoietic stem cells and differentiating into various blood cell types.

The initial site of hemopoiesis in the developing fetus, starting from the second week of gestation, located in the wall of the yolk sac.

The site of hemopoiesis during the fetal period, taking over from the yolk sac, starting from the third month of gestation, located in the liver.

The site of hemopoiesis starting from the fourth month of gestation, located in the spleen, lasting for a short period.

The site of hemopoiesis starting from the fifth month of gestation, located in the red bone marrow, becoming the primary site after birth.

The primary site of hemopoiesis in adults, located within the cavities of bones.

Multipotent stem cells found in the bone marrow and peripheral blood, capable of self-renewal and differentiating into all blood cell types.

The process of erythrocyte (red blood cell) formation, starting with a proerythroblast and progressing through various stages.