Midterm 1 Information

The following are suggested learning objects from the lectures. Generally, know enough to elaborate on each learning objective in a few sentences in your own words. Trying to explain each learning objective out loud to a classmate or friend is an excellent way to check how well you really understand the concepts involved. You do not need to memorize minute details from the reader or handouts. Focus on the big picture and you will be fine. I would suggest looking at the past exams on reserve in Moffitt to get a sense of what kind, and at what level, of questions that are asked. Good luck.

Sample Questions and Answers From Past Exams

LECTURE TOPICS TO KNOW

Introduction

Understand the concept of plasticity as it relates to growth and development throughout life, especially during critical periods. Examples of critical periods include the prenatal period and puberty. Be able to give 2 examples of plasticity in response to genetic or environmental cues. One example would be development of the breasts during pregnancy in preparation for lactation. Another would be hypertrophy and increased microcirculation in the leg muscles of a person training for a marathon. Be able to think of other examples as well.

Gametogenesis Spermatogenesis
Know the histological arrangement of Leydig and Sertoli cells in relation to the seminiferous tubules of the testes. Know the anatomical pathway followed by spermatozoa from seminiferous tubule to urethra Know the stages of development of male gametes from germ cell to spermatozoa. Know the progression of meiosis, general cell morphology, and position within the seminiferous tubule at each stage. Understand when in the lifetime of the male these stages occur. Know the reproductive hormones produced by the hypothalamus, anterior pituitary, and Leydig and Sertoli cells. Understand the basic mechanisms of feedback control among these three levels.

Oogenesis
Understand the process of follicular development and degeneration in the ovaries in relation to the menstrual cycle. Know the structure of the developing ovarian follicle, including theca and granulosa cells and ovum. Know the stages of development of female gametes from germ cell to ovum, particularly with respect to the stages of meiosis. Understand when in the lifetime of the female these stages occur. Know the predominant hormones produced by the hypothalamus, anterior pituitary, granulosa cells, theca cells, and corpus luteum. Understand the basic mechanisms of feedback control among these hormones. Understand the regular variation in hormone levels that regulates the menstrual cycle.

Genetic Sex Determination
Understand the normal contributions of male and female gametes to determining the genetic sex of the offspring. Be familiar with the variety of chromosomal disjunctions related to sex differentiation, including XO (Turner syndrome), XXX, XXY (Klinefelter syndrome), XYY, and YO (incompatible with life). Know the characteristic signs and symptoms of each.

Fertilization
Know the overall morphology of mature spermatozoa, particularly the specializations that facilitate their role in fertilization. Know the basic configuration of the ovum after ovulation, especially in relation to the zona pellucida and corona radiata. Understand the basic stages involved in union of the gametes, including capacitation of the sperm, the acrosomal reaction, and fusion of the nuclei.

Preimplantation and Implantation
Know the initial stages of cell division that occur prior to implantation, including the morula and blastocyst. Know the differentiation of cells into trophoblast and embryoblast around the time of implantation. Understand the basic process by which the blastocyst initially implants in the endometrium (see Placenta and Fetal Membranes below). Know the basic mechanism explaining why the maternal immune system does not reject the embryo as foreign tissue.

Infertility and Assited Reproductive Technologies
Know the common causes of infertility and the treatments and indications for the treatments discussed in lecture. Omit cytoplasmic transfer.

Placenta and Fetal Membranes
Understand the basic development and structure of the placenta, including the regions of the three decidua, chorion, and amnion. Be able to trace the path of fetal and maternal blood through the placenta, keeping clear that that they do not mix but rather that transfer of substances between fetal and maternal blood takes place across layers of fetal cells. Know the main functions of the placenta: respiration, nutrition, excretion, protection.

Embryonic Development
Understand the process of gastrulation, by which the three germ layers are formed: ectoderm, mesoderm, and endoderm. Know the general types of tissues derived from each germ layer.

Embryology of the Reproductive System
Know that morphological characteristics of the male and female reproductive tracts do not begin to differ until the seventh week of gestation, even though the genetic sex of the embryo is determined by fertilization. This is the indifferent stage of sexual development. Understand that differentiation of male gonads and external genitalia is in response to androgen secretion, which are the messengers of sex determination in the male. If androgenic hormones are absent or if tissues fail to respond appropriately in the male, then sex characteristics default to the female pattern. Conversely, exposure of the female embryo or fetus to high androgen levels has a masculinzing effect (male pseudohermaphriditism). Initial differentiation of the testes results from a development sequence activated by testis-determining factor (TDF), encoded in the sexdetermining region of the Y chromosome (SRY); ovaries develop in its absence. Understand the roles of the following in sexual differentiation: SRY, TDF, Leydig cells, Sertoli cells, testosterone, dihydrotestosterone, MIF, Mullerian ducts, and Wolffian ducts.

The Normal Newborn and Newborn at Risk
Understand that fetal lungs are compressed with fluid filled potential spaces that become alveoli. The first breath of the newborn is a high pressure breath that inflates the lungs and begins to move the fluid out of the alveoli. Know and be able to use the Apgar test. Know the common causes of increased risk. Know the problems of prematurity. Know why K+ and eye drops are administered to the neonate.

Morphologic Development of the Nervous System
Understand the process of formation of the the neural plate, neural folds, and neural tube in the embryo (neurulation). Have a basic understanding of how the brain and spinal cord develop from the neural tube. Know that closing of the ends of the tube is a critical event, the failure of which leads to severe birth defects. Know that the tube folds and thickens at the cranial end to form the various levels of the brain. Memorize the the three primary brain vesicles (forebrain, midbrain, hindbrain), and know the derivation of the secondary brain vesicles from them (mnemonic: "Tell Di, Mes met My" = "Telencephalon Diencephalon Mesencephalon Metencephalon Myelencephalon"). Know how the basic adult brain structures derive from the secondary brain vesicles. Know the five types of cells derived from the neuroepithelium and any functions or locations discussed in lecture.

Biochemical Development of the Nervous System
Understand how and why the embryonic CNS has significant dependence on anaerobic respiration, a pattern which shifts to aerobic respiration following birth with greater availability of oxygen. Be familiar with the significance of myelination, the formation of lipid insulation around axons. You do not need to know details about mechanisms of myelination, but myelination is critical for precise, rapid conduction of signals and therefore for proper functioning of the nervous system. It begins in the fourth month of gestation and continues well into childhood. Know that neurons lose their ability to replicate upon differentiation. However, they retain the ability to continually remodel their connections to other neurons. This process is critical for growth, memory, and adaptation. Know the signs of symptoms of cretinism, and the role of thyroid hormone in normal postnatal development of the nervous system.

Functional Development of the Nervous System
Understand that the mature brain is wired with great precision to process sensory input and generate our thoughts and behavior. At birth, the pattern of neuronal connections necessary for optimal brain function is only roughly worked out. The rough patterns are refined over time in response to the accumulating experiences of the child. Know that perinatal behavior (of the fetus and infant around the time of birth) is notable for strong reliance on reflexes, such as the suckling reflex. Understand that different parts of the nervous system develop at different rates and which parts are relatively more developed at birth.

Sexual Differentiation of the Nervous System
Understand generally that steroid hormones affect the development not only of the reproductive organs, but also have specific actions on parts of the brain, where populations of neurons with steroid receptors exist. One specific example is the action of androgens on the sexually dimorphic nucleus of the preoptic area (SDN-POA), a part of the hypothalamus that is probably involved in sexual behavior and in regulating the release of GnRH from the anterior pituitary. It is typically larger in (heterosexual?) males than in females.

Establishment of Fetal Circulation
Be able to trace the path of a drop of blood through the fetal and placental circulatory system prior to birth. Understand the anatomical basis for shunting oxygenated blood to critical organs. Be able to trace the path of a drop of blood through the infant following birth, and understand how the new circulatory pattern is established. Understand the basic adaptations by which the fetus thrives in a relatively low-oxygen environment, including production of fetal-type hemoglobin, production of higher levels of hemoglobin in the fetus, and the Bohr effect of oxygen-carbon dioxide exchange in the placenta.