Online Microbiology and Biology Notes
Zebrafish Development The teleost fish Danio rerio is commonly known as the zebrafish. It is a common small‐bodied tropical, freshwater species originally from South Asia. The fish is a part of the Cyprinidae family, which includes carps, true minnows, barbs and related genera. The Danio genus (formerly Brachydanio) contains more than 40 related species along with the zebrafish (Danio rerio). Zebrafish as a Vertebrate …
Implantation- Process, Events, Significance The term “implantation” is used to describe the process of attachment and invasion of the uterus endometrium by the blastocyst (conceptus) in placental animals. It begins at the end of the first week and is completed by the end of the second week of gestation. Implantation occurs in the endometrium of the uterus superior in the …
Heart Embryology- Development of the Heart The heart is a muscular organ located in the middle mediastinum that pumps blood through the circulatory system. It is one of the earliest differentiating and functioning organs in the human body. In human embryos, the heart begins to beat at about 22-23 days, with blood flow beginning in the 4th week. It begins very early …
What is Developmental Biology? It is the field of biology that studies the processes by which multicellular organisms grow and develop, controlled by their genes. It involves the study of mechanisms of development, differentiation, and growth in animals and plants at the molecular, cellular, genetic and evolutionary levels. It also encompasses the biology of regeneration, asexual reproduction, metamorphosis, and the growth and differentiation of stem cells in the adult …
Stages of Childbirth Labor is a physiologic process during which the fetus, its associated membranes, the umbilical cord, and the placenta are expelled from the uterus. During most of the months of pregnancy, the uterus undergoes periodic episodes of weak and slow rhythmical contractions called Braxton Hicks contractions. Contractions become progressively stronger toward the end of pregnancy; that start stretching …
Drosophila Development- Stages, Significance The fruit fly Drosophila melanogaster has been extensively studied for over a century as a model organism for genetic investigations. It also has many characteristics that make it an ideal organism for the study of animal development and behavior, neurobiology, and human genetic diseases and conditions. Image Source: biology.kenyon.edu Developmental Stages of Drosophila The development of Drosophila can be …
The nematode worm Caenorhabditis elegans is a small (1 mm long), unsegmented, vermiform, free-living soil nematode. It is a relatively simple, and precisely structured organism, extensively used as a model organism for molecular and developmental biology. The body of an adult C. elegans hermaphrodite contains exactly 959 somatic cells, whose entire lineage has been traced through its transparent cuticle. Its genome has …
The preimplantation period of human embryo development is remarkable and characterized by successive changes in terms of genetic control, physiology, and morphology of the embryo. Blastocyst (Greek, blastos= sprout + cystos = cavity) is a distinctive stage of mammalian embryo development, characterized by a hollow cellular mass that forms in early development. It is an embryo that has developed for five to six days after …
DNA methylation is a process by which methyl groups are added to the DNA molecule. It is an epigenetic mechanism that occurs by the addition of a methyl (-CH3) group to DNA, thereby often modifying the function of the genes and affecting gene expression. The most widely characterized DNA methylation process is the covalent addition of the methyl group at the 5-carbon of the cytosine ring resulting in …
‘Embryo transfer’ refers to the transplantation of a mammalian preimplantation embryo into the reproductive tract of a recipient female so that it may implant and continue to develop to birth. Mammalian embryos of many species can develop in vitro from fertilization to the blastocyst stage (approximately 100 cells), but at this point, they must implant in the uterus in order for embryogenesis …