Difference between revisions of "User talk:Z3332337"
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*Optic stalks project from diencephalon.
*Optic stalks project from diencephalon.
Revision as of 12:33, 3 October 2012
NON ASSESSABLE MATERIAL/DRAFT WORK
--Z3332337 11:52, 25 July 2012 (EST)
ANAT2341 – LAB 1 25/07/12
- The type of cells in the zona radiata are the ‘granulosa’ cells.
- Zona pellucida is a specific extracellular matrix to the (development) of the oocyte. Consists of 3-4 thick glycoproteins made by the oocyte itself and the granulosa cells are attached to the outside.
- The fusion of the spermatozoa to the zona pellucida stimulates the oocyte to continue into the final stages of meiosis.
- The production of the final polar body (which contains half the chromosomes of the original germ cell) is also stimulated.
Occasionally, the 3rd polar body is made by the 1st polar body which also undergoes meiosis. NB: The polar bodies are “trash bags” of the oocytes.
- In meiosis the abnormality trisomy 21 (down syndrome) “leaves behind chromosome 21” (ie: isn’t separated properly).
Two other trisomy’s exist, trisomy’s 18 & 13 (occur in this order). Major genetic abnormalities are spontaneously aborted in the first 2 weeks of development because they are incompatible with proper development.
- The proliferating spermatagonia (make MORE spermatogonia which) are the ones who continue on to complete meiosis, which create spermatids (haploid cells).
- These daughter cells are initially cross-linked until maturation of spermatid into spermatozoa.
- FINAL (functional) MATURATION, doesn’t occur in the epididymis (although altered here).
It actually occurs after ejaculation into the vagina where it undergoes capacitation. The pH in the vaginal canal causes this change.
Sperm undergo morphological, physiological and biochemical changes during the journey through the female reproductive tract; a process called Capacitation.
Semen contains factors that do not allow the sperm to penetrate the ovum and these are removed in the female reproductive tract.
Capacitation needs to occur before the sperm are capable of penetrating and fertilising an ovum.
Many sperm are required to dissolve the zona pellucida of the ovum, but only one gets the chance to fertilize.
- NB: the ovary is located in the PERITONEAL CAVITY.
- Ovarian follicle atresia: atresia refers to the degeneration and subsequent resorption of one or more immature ovarian follicles.
NB: this can happen at any time in the cyle.
- The medullary region of the ovary is highly vascularized because hormones (FSH and LH) are being brought in to regulate menstruation and pregnancy (negative feedback loop).
Supported by the granulosa cells.
Follicle Classification The above images show the histological changes that occur with follicle development (folliculogenesis). In humans, this entire process occurs over the timecourse of at least 3 menstrual cycles. This means that within the ovary during each cycle (at any point in time) many follicles can be either developing (folliculogenesis), regressing (atresis) and only a single follicle will be selected as ready for release. The selected follicle readied for release, generally one of the largest antral follicle, and can be classifed or described as: an antral preovulatory follicle or Graafian follicle or type 8 follicle (depending upon the classification used).
Classification systems - There are several different nomenclatures for the stages of follicle maturation (shown below) all of which makes the literature very confusing. The simplest is primordial, preantral, antral, Preovulatory (Graffian). You can also use the 5 step follicle classification: Primordial, Primary, Secondary, Tertiary, Preovulatory. Note that some classifications refer to the antral follicle as a secondary follicle and do not use the term tertiary follicle.
- Primordial Follicle - Alternative nomenclature: small follicle or type 1, 2, 3 (25 cells) less than 50 micron diameter.
- Preantral Follicle - Alternative nomenclature: preantral follicle or type 4 (26-100 cells), type 5 (101-300 cells) up to 200 micron diameter.
- Antral Follicle - Alternative nomenclature: small antral type 6 (301-500 cells), large antral type 7 (501-1000 cells) small antral 500 micron diameter, large antral 1000-6000 micron diameter.
- Preovulatory Follicle - Alternative nomenclature: largest antral follicle or Graafian follicle or type 8 (>1000 cells) greater than 6000 micron diameter.
NB: IT TAKES MORE THAN 1 CYCLE TO MATURE TO BE SELECTED TO BE RELEASED IN OVULATION.
- Microtubule organisational centre radiates for motility.
- Acrosome (‘acrosomal head’) is a modified golgi apparatus.
Acrosome is a large vesicle, containing enzymes and proteins that enable sperm to penetrate oocyte by dissolving the zona pellucida.
- Mitochondria are tightly packed within the mid-tail of the spermatozoa to generate the ATP required to drive the whip-like movements of the tail.
- There are 3 types of cells: germ, support and hormonal.
- Only 2 cells (sertoli and spermatogonia).
ANAT2341 – LAB 2 01/08/12
• Purposes for research into fertilisation:
- Farming industry
PubMed journal articles: Sperm penetration through the cumulus & Sperm-Egg Interaction.
• The oocyte and spermatozoa alike, undergo reactions for sperm membrance fusion, cortical reaction & the 2nd meiotic division. Calcium flooding can trigger the cortical reaction and Cyclohexamide prevents the polarisation of the 2nd polar body, and therefore these mechanisms alter the natural pathway.
• Imprinting is...
Pregnancy - Week 1
• The uterine tube is a CILIATED EPITHELIUM.
• The zona pellucida (pale ring around te ooccyte) is a specialised extra-cellular matrix made of GLYCOPROTIENS (ZP1, ZP2, ZP3, & ZP4 in humans). These glycoproteins are species specific. Its functions are:
- Protection and flexibility - Protects blastocyst as well while proliferating - Patterns the development of the blastocyst and have a squamous morhphology. - Sperm receptor - Prevents implantation - Prevents polyspermy; modified by the cortical granules.
• IMPLANTATION: takes ~1 week (specific to week 2).
• The inner cell mass of the blastocyst forms the EMBRYO.
• Epigenetics: “re-programming” of the PATERNAL GENETICS by mechanisms other than the changes in the underlying DNA sequence.
• Telomeres: at the end of the chromosomes are related to aging and are maintained by TELOMERASE. Telomere length
• In the 2nd week, TWO layers of trophoblasts develop. - Peripheral: CYTOTROPHOBLASTS - Central: SYNCITIOTROPHOBLASTS
• Later in the movie the amniotic cavity forms adjacent to the epiblast layer(blue) and spaces in the syncitiotrophoblast layer are filled with maternal blood, lacunae.
• In this week , the embryo is referred to as the BILAMINAR EMBRYO.
• In Carnegie Stage 4, implantation starts.
• The endometrium is called the DECIDUA. DECIDUA BASALIS at the time of implantation and “DECIDUALISES” the rest of the of the uterus. - “That part of the decidua that interacts with the trophoblast is the decidua basalis (also called decidua placentalis). The remainder of the decidua is termed the decidua parietalis or decidua vera. Also, there is the decidua capsularis, which grows over the embryo on the luminal side, enclosing it into the endometrium and surrounding the embryo together with decidua basalis.” 
ANAT2341 - Lab 3
Endoderm: lines the yolk sac
Three ExtraEmbryonic cavities: • Chorionic • Amnionic • Yolk (?)
Three IntraEmbryonic cavities: • Pericardial • Pleural • Peritoneal
Extra-embryonic mesoderm: covers all surfaces of extra-embryonic spaces.
Transverse septum: lies beneath heart, marks site where amniotic cavity meets yolk sac.
Folding occurs at same time of somite formation.
From week 4 the yolk sac is separated by “yolk stalk” in the mid gut; and the rest of the embryo.
Desidua basales: where placenta forms
- Amniotic sac increases in volume (allows fetus to develop with equal pressure around and fetus swallows amniotic fluid to ready the GIT for peristalic motions) & fills chorionic space; while yolk sac decreases.
Stage 7 imaging:
• Kyoto collection • Bright field • Scanning Electron Micro (SEM)
• In Carnegie stage 10, the heart is anatomically “upside down” and then correects itself when the cardio tube folds. CRL: Crown Rump Length
ANAT2341 Lab 4
• Myoglogin: higher presence in slow twitch muscle fibres (than fast twitch), therefore redder.
• Neuronal inputs into muscle are SENSORY & MOTOR. Don’t innervate just ONE muscle fibre, they innervate a group via:motor end plates (depending on the function of the muscle). Spindle fibres (stretch fibres??). Dorsal root ganglia are proprioceptors.
• Actin fibres. Big R type(marathon). Small r type (sprinters).
• Possible to change fibre types (fast slow) because of muscle plasticity.
• > 50yo lose muscle mass and preferential loss of fast twitch fibres.
• Duchenne muscular dystrphy -> loss of Dystrophin (???)
• Sybcitia: multinuclei bounded by one plasma membrane (ie: osteoclasts)
• 2 stages of myogenesis (of a myotube) . 1) 12-14 days post-coitum (in mouse). Myoblasts fuse together and scleraxis allows the dev. Of tendoms. Myosin heavy chains. 2) after Formation of myotube innvervation occurs. 2dary myogensis (myosin heavy chain gene expression (embryoic and neonatal).
• How does muscle know that it’s excerising? Sensing the “load” and the motor/sensory input, protiens whic h detect stretch to detect the load, etc etc.
• Exercise 1: Measuring the difference between the area & / diameter of cells. Volume (amt of proteins in one cell compared to normal cell).
• Exercise 2: How do we achieve hypertrophy? Regeneration process (activate satellite/stem cells) or nuclei becomes MORE active (hence there is an increase in cell size, not cell number).
• Do we need satellite cells to induce muscle hypertrophy? Pax7 spec. Expressed in satellite cells, but essential to muscle dev.
• Cre: DNA recombinase. CRE-ER: Cre DNA recombinase fused to the estrogen receptor. Tamoxifen (estrogen analog) binds to estrogen receptor. Ie: exposing satellite cells to tamixifen will kill the cells becase of a side chain???
• Syngergist ablation: knocking out supporting muscles to engage other muscles to induce hypertrophy by overloading it.
• Control: no satellite removal. Variable: muscle removal. SA-2 muscle weight increase.
• What is the importance of maintenance of nucleus/cytoplasmic ratio? Muscle control and maintaining jurisdiction of nucleus control.
• Exercise 3: Experimental induction of muscle fibre type change Using Chronic low frequency stimulation (CLFS). Stimulate the common peroneal nerve (10 stimulations per sec) over 21 days. Tib ant muscle is rich in fast twitch fibres. ABCD – control mouse, black stain few slow fibres compared to fast. HGFI – experimental mice, small increase in slow twitch fibres.
• MyHC (Myosin heavy chain) 1 – small increase
• MyHC 2a – Drastic increase.
• All MyHC (but not 2x) – ?? hard to est
• MyHV 2b – not particularly changed. Probably not had time in the 21 days. 2b -> 2x, neighbour rule.
ANAT2341 Lab 9 26/09/12
Embryonic development ends at week 8
By end of week 8, eyelids are present. Upper and lower eyelids grow together and the fuse and later in development they separate.
Gland is ECTODERMAL in origin.
Hypothalamus – neuroendocrinal with lots of glia.
Diencephalon is a secondary brain vesicle of the primary brain vesicle of the prosencephalon.
Rathke’s pouch is still present but later lost.
Trigeminal ganglia are the largest in development, seen from as early as week 3?
Vomer in nasal organ: in animals important in reproduction activated when female on heat.
Palatal shelves still communicating with each other.
(Thymus) Immune function is not active pre-natally as mother and placenta are compensating.
Changes of thymus with aging: gets smaller (decrease in volume) and increase in fat cells -> thymic involution Fetal cortex of medulla has different laminations to an adult and has different secretory action to an adult. Cortex isn’t fully developed until 3 yrs.
Gonads have an important endocrinal role for the development of the internal genital tract (small kidney with large gonads beneath and adrenals above). Mainly nephrogenesis is later throughout development, mainly collecting tubules now. That is why it’s so small and because the maternal system is dealing with the waste.
Week 10!!!!! Hormone detection!!!!
Theory of endocrine systems in exam: know 2 endocrine organs in detail!!!
ANAT2341 Lab 10 3/10/12
- Week 4 is when we 1st see the sensory component appear.
- Cranial neuropore will close before the other neuropore. If they don’t close, there is an association of neural tube defects (from lack of folate – homocystiene – metabolism). Results in anencephaly. No extension of mixed nerves from spinal cord = abnormalities in limbs and possibly urinary tract.
- Columnar epithelium associated with surface ecto (closely assoc with hindbrain), whereas in the indentation there is more cuboidal cells. Surface ectoderm will then fuse and form the otic placode proper = otic cyst!! At the level of the 2nd pharyngeal arch.
- All the features associated with hearing are at the level of the 2nd pharyngeal arch.
- Nasal placode at the level of the frontonasal prominanace with the nasal placode. Doesn’t fold into the head. Has a lateral and ventral region.
- Just behind the 1st pharyngeal arch is the optic placode and form the lens component of the eye. Optic placode is lost and leaves behind the lens.
- Adenohypophysis/pituitary placode just in front of buccopharyngeal arch.
- Stem cells form the innermost layer of epithelial cells is mitotically active and migrates outs to form the motor and sensory neurons. Note: the neural tube is not the same thickness the entire way.
- Space within the neural tube = ventricular cavity, is continuous and maintained in the adult. Primordia of vent cav. At this stage not filled with CFS yet, filled with amniotic. Will fill with CFS when CHORIOID PLEXUS forms, a modified placenta.
- Beneath the mylencephalon is the spinal cord.
- Pontine is an ‘M’ structure. Midline is notochord and when you cut through is, you’ve cut all the way through the neural cord.
- 1st pharyngeal arch forms the tympanic membrane.
- Prosencephalon forms diencephalon and ‘end brain’ lies on top of that and forms cortical... something??
- Optic vesicle is an outward growth of the diencephalon (neural tube). Is not separated to but connected.
- Pigmented layer of retina and other retina has a space which is lost because they fuse.
- Hyloid blood vessels (in vitrious) are transient blood vessels lost in post gestationally.
- Rectus eyes muscles are neural crest in origin (not mesenchyme, but ectomesenchyme).
- Optic stalks project from diencephalon.
- Throughout the entire fetal period, continuously making neurones and lose some from programmed cell death. Neurones and glia are formed from the same stem cell population. Also, mylenation occurs post-natally and therefore a change in conduction velocity changes.