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October, 2006
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Ovary: The reproductive organ (Gonads) in female animals. In vertebrates, the ovary contains two functional parts: the Ovarian follicle for the production of female germ cells (Oogenesis); and the endocrine cells (Granulosa cells; Theca cells; and Luteal cells) for the production of Estrogens and Progesterone.

Purification and Analytics of a Monoclonal Antibody from Chinese Hamster Ovary Cells Using an Automated Microbioreactor System

1Center for Drug Evaluation and Research, Office of Product Quality, Office of Biotechnology Products, Division of Biotechnology Review and Research II, U.S. Food and Drug Administration

JoVE 58947


Fruit Development, Structure, and Function

JoVE 11110

Fruits form from a mature flower ovary. As seeds develop from the ovules contained within, the ovary wall undergoes a series of complex changes to form fruit. In some fruits, such as soybeans, the ovary wall dries; in other fruits, such as grapes, it remains fleshy. In some cases, organs other than the ovary contribute to fruit formation; such fruits are called accessory fruits.

Fruits can be classified based on the number of flowers and the structure of the carpels involved in their formation. Fruit that develops from a single flower with one carpel or multiple, fused carpels are classed as simple fruits. Aggregate fruits develop from multiple, separate carpels of a single flower. In contrast, multiple fruits are produced when multiple carpels of many flowers that make up an inflorescence combine to form a single fruit. Fruits help protect and disperse a plant’s seeds. Many fruits depend on biotic factors, such as fruit-eating animals, to disperse seeds. Undigested seeds in fruit can be remotely dispersed in animal droppings. Other fruits rely on abiotic factors, such as water and wind, to disperse seeds. Some fruits can even disperse themselves - for example, mature pea pods explode and release seeds. Water-dispersed seeds often have light, buoyant fruit. For example, coconuts float and have hard exteriors, and their seeds can still germinate

 Core: Biology

The Angiosperm Life Cycle

JoVE 11108

Plants have a life cycle split between two multicellular stages: a haploid stage—with cells containing one set of chromosomes—and a diploid stage—with cells containing two sets of chromosomes. The haploid stage is the gamete-producing gametophyte, and the diploid stage is the spore-producing sporophyte.

Today, most plants grow from seeds and produce flowers and fruit; such plants are called angiosperms. Angiosperms begin as seeds—structures consisting of a protective seed coat, a nutrient supply, and an embryo. The seed develops into a sporophyte—the familiar, flower-producing plant form. The reproductive life cycle of angiosperms begins with flowering. Stamens and carpels contain sporangia, structures with spore-producing cells called sporocytes. Sporophytes produce spores as either eggs or sperm, depending on their origin. For example, male spores—called microspores—are produced within anthers at the tips of stamens. A microspore develops into a pollen grain—the male gametophyte. A pollen grain contains a tube cell and a generative cell, which develops into sperm. A carpel consists of an ovary and its ovules. Female spores, called megaspores, are produced within ovules. A megaspore develops into an embryo sac—the female gametophyte—which contains the egg. Pollination allows

 Core: Biology


JoVE 10907

During fertilization, an egg and sperm cell fuse to create a new diploid structure. In humans, the process occurs once the egg has been released from the ovary, and travels into the fallopian tubes. The process requires several key steps: 1) sperm present in the genital tract must locate the egg; 2) once there, sperm need to release enzymes to help them burrow through the protective zona pellucida of the egg; and 3) the membranes of a single sperm cell and egg must fuse, with the sperm releasing its contents—including its nucleus and centrosome—into the egg’s cytoplasm. If these steps are successful, the genetic material of the male and female gametes combine, and mitotic cell division commences, giving rise to a diploid embryo. The binding of the sperm and egg cell brings about various changes, among them the production of waves of calcium ions (Ca2+) pulsing through the egg cell. Such oscillations are initiated by sperm-egg fusion and result from both the release and uptake of endogenous Ca2+ in the endoplasmic reticulum of an egg cell and the simultaneous discharge and intake of such ions from the egg’s extracellular environment. Importantly, calcium signaling modifies the egg by causing vesicles, called cortical granules, that lay directly below its plasma membrane to release their contents into the open space bene

 Core: Biology


JoVE 10906

In human women, oogenesis produces one mature egg cell or ovum for every precursor cell that enters meiosis. This process differs in two unique ways from the equivalent procedure of spermatogenesis in males. First, meiotic divisions during oogenesis are asymmetric, meaning that a large oocyte (containing most of the cytoplasm) and minor polar body are produced as a result of meiosis I, and again following meiosis II. Since only oocytes will go on to form embryos if fertilized, this unequal distribution of cell contents ensures that there are enough cytoplasm and nutrients to nourish the early stages of development. Second, during oogenesis, meiosis “arrests” at two distinct points: once during embryonic growth and a second time during puberty. In mammals, oocytes are suspended in prophase I until sexual maturation, at which point meiosis I continues under hormonal influence until an egg precursor cell is released into a fallopian tube. At ovulation, the precursor exits the ovary and, only if fertilization occurs, is stimulated to complete meiosis II and form a complete egg. Defects during oogenesis can result in severe consequences. In particular, problems with chromosome segregation during either meiosis I or meiosis II may lead to an embryo being aneuploid, meaning that it contains an abnormal number of chromosomes. Increased age elevates a woman

 Core: Biology

Plant Diversity- Concept

JoVE 10598

From Water to Land

Kingdom Plantae first appeared about 410 million years ago as green algae transitioned from water to land. Though challenging, this transition benefited early colonizers in several ways. Initially, most living organisms (including plants and animals) were ocean dwelling, making aquatic environments crowded and highly competitive. In contrast, land was a relatively…

 Lab Bio

Introduction to Seed Plants

JoVE 11089

Most plants are seed plants—characterized by seeds, pollen, and reduced gametophytes. Seed plants include gymnosperms and angiosperms.

Gymnosperms—cycads, ginkgo biloba, gnetophytes, and conifers—typically form cones. The pollen cones contain male gametophytes. The ovulate cones contain female gametophytes and form exposed seeds when fertilized.

Angiosperms, the most diverse and ubiquitous group of land plants, form flowers, and fruit. Like the cones of gymnosperms, the flowers and fruit of angiosperms enable sexual reproduction. Flowers facilitate pollen dispersal. The fertile flower structures—stamens and carpels—contain male and female gametophytes, respectively. Fruits facilitate seed dispersal, often forming after flowers have released pollen. As seeds develop from a flower’s fertilized ovules, the ovary wall thickens, forming a fruit containing seeds. Angiosperms were historically categorized as monocots or dicots based on their number of cotyledons—or seed leaves. However, based on genetic evidence, most species classically considered dicots are now called eudicots. Legumes (e.g., beans) and most well-known flowering trees (e.g., oaks) are eudicots. The other former dicots belong to one of four small lineages. Three of these—Amborella, water lilies, and star anise and i

 Core: Biology

Meiosis II

JoVE 10768

Meiosis II is the second and final stage of meiosis. It relies on the haploid cells produced during meiosis I, each of which contain only 23 chromosomes—one from each homologous initial pair. Importantly, each chromosome in these cells is composed of two joined copies, and when these cells enter meiosis II, the goal is to separate such sister chromatids using the same microtubule-based network employed in other division processes. The result of meiosis II is two haploid cells, each containing only one copy of all 23 chromosomes. Depending on whether the process occurs in males or females, these cells may form eggs or sperm, which—when joined through the process of fertilization—may yield a new diploid individual. Although the goal of meiosis II is the same in both males and females—to produce haploid egg or sperm cells—there are some critical differences in this process between the sexes. For example, in a woman’s egg precursor cells, the meiotic spindle apparatus responsible for separating sister chromatids forms off to one side, near the periphery. This asymmetry allows for two cells of unequal sizes to be produced following meiosis II: a large egg, and a smaller polar body that dissolves. This division of cytoplasm ensures that the egg contains enough nutrients to support an embryo. The position of the meiotic spind

 Core: Biology

Pelvic Exam III: Bimanual and Rectovaginal Exam

JoVE 10163


Alexandra Duncan, GTA, Praxis Clinical, New Haven, CT

Tiffany Cook, GTA, Praxis Clinical, New Haven, CT

Jaideep S. Talwalkar, MD, Internal Medicine and Pediatrics, Yale School of Medicine, New Haven, CT

A bimanual exam is a…

 Physical Examinations II
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