Weeks 7 and 8 of Embryonic development and External Embryo Appearance
Week 7 of development ◦CONNECTION BETWEEN THE GUT AND YOLK SAC consists of only the small yolk stalk Umbilical herniation occurs; intestines during rotation of the gut enter the extraembryonic coelom in the proximal portion of the umbilical cord ◦THE LIMBS change markedly during this week The forelimbs project over the heart Notches are seen […]
Weeks 4 to 6 of The Embryonic Development
During this relatively short embryonic period (weeks 4 to 8), one sees the beginnings of all major internal and external structural (organ and organ systems) develop during which time the 3 germ layers give rise to specific tissues and organs – the period of organogenesis. The shape of the embryo changes, and major features of the […]
Week 3 of Embryonic Development
Trilaminar Germ Disk Embryo Formation and Gastrulation week 3 is a period of rapid development of the conceptus coinciding with the first missed menstrual period. By days 15-16, the embryo is 1.5 mm long, and one clearly sees the primitive streak, Hensen’s node, and the notochordal process- All morphologic indications characteristic of gastrulation. The latter […]
Week 2 of Embryonic Development
Week 2 is about the implantation process and blastocyst differentiation. Note that all cells produced from the initial fertilization event are defined as the “conceptus” and will include cells with both embryonic and extraembryonic features. In the conceptus, this is a period of blastocyst “hatching” rapid blastocyst differentiation into extraembryonic and embryonic tissues and proliferation. […]
Week 1 of Embryonic Development
The first week of human development begins with fertilization of the egg by sperm forming the first cell, the zygote. Cell division leads to a ball of cells, the morula. Further cell division and the formation of a cavity in the ball of cells forms the blastocyst. Initially, there is a halving of chromosomal content in the gametes […]
Implantation
Implantation is the stage in embryonic development in which the blastocyst hatches as the embryo, and adheres to the wall of the uterus. Once this adhesion is successful, the female is considered to be pregnant and the embryo will receive oxygen and nutrients from the mother in order to grow. We can learn this lesson […]
Fertilization
Fertilization is the union of male(sperm) and female(oocyte) gametes to form a zygote and marks the beginning of the pregnancy. Embryonic life begins with fertilization. Fertilization process require 24 hours. During this lesson we need to discuss about Ovulation Getting the spermatozoa ready Key steps of fertilization The formation of the zygote Abnormal Fertilization Ovulation […]
Gametogenesis
Gametogenesis is the production of gametes from haploid precursor cells. In animals and higher plants, two morphologically distinct types of gametes are produced (male and female) via distinct differentiation programs. Animals produce a tissue that is dedicated to forming gametes, called the germ line. Now we are going to learn about the, The Germ Line Sexual […]
Introduction To Embryology
Embryology is the branch of biology that studies the prenatal development of gametes, fertilization, and development of embryos and foetuses. Additionally, embryology encompasses the study of congenital disorders that occur before birth, known as teratology. Embryology can be mainly studied under two main divisions. They are EMBRYOGENESIS and ORGANOGENESIS. Embryogenesis is the process of initiation and […]