Unit 3: Reproductive Biology

Embryogeny: (Embryo formation) The process of formation & development of embryo in plants is called embryo -geny. Embryo to the developed zygote which is the combi -nation of made gamet or, egg The embryogenesis follows diggn, patterens of cell division, where as tygote divides in angiospretum. The first division is treansversed resulting for small epical (ca) and a larger basar cell (eb). The epical cell projects into embryosae, wherce as basal cell lies next to micropyle. The development patteren divides în monocotyledons & dicotyledons. * Embryo development in dicotyledon. ~~ The epical cell of the two celled pro embryo divides Longitudinally otro transversalny & the basal cell remains on divided orci, may further divided transversally Schnarg and Johansen divided embryo into 5. typeset Ay Terminal cells divides congitudinaly crusiter on, onagrad type fix Astercard type o Terminal cells divides by transverse wall By solanad type 49% caryophyllad type Chenopodiad type The basal cell plays on fact an only a siκαι minor part in development as embryo. →113 found in annonaceae, brassicaceae, Ronun- culacea,. ii Asterad The basas cell and the opical cell con tribute fore the development of lembreyo. It is found in astraceae, vitaceae. fits solanad ~ The bascy cell doesn't play any role oll, has minor role in ombrejo development The bascu cell forms suspensor of two only more cell. Ex Found in solanaceae, thesceae ivy caryophyllad The basal cell doesn't divide and is sus- -pensor is formed, it developes from the terminal cell. It is found in caryophyllaceae & crassulaceae v cenopodiad The basal cell as well as the Hercminal cell participate in the formation og embryo. It is sound in borragenocere & chenopodaceae. Johansen reported oth type of based on vertical embryogenic vi Piperad type In this girst division of zygote is verticas ort, can be tongitudinal. It is found in corcanthaceae and pipercaceae. Pemate Cycxmetophyle (Embryo sac) The Female gametophyte is called embryosac. It is mostly chalatal and grows mainly euong the micropile It undergoes several nuclear mitotic division and forums & nucleus. The first sporce is called megasporce. Durring megasporragenesis the diploid megaspore mother call undergoes meiosis and forums haploid meg- aspores which develops into haploid stemale gameto- phyte by the process megagametogenesis * Megasporrogenesis *The process of formation of megersporce grom megaspore mothere cell (MMC) is called megasp- orogenesis The nucleus towards the microptlar end differ- entiates a hypodermal cele into an archespotial. initial The archesporias initial divides perciclinary to forem outer primary perietal cell & innere preimcury sporrogenous cell. → the perimeury sporcogenous cell foreing the megaspores modhere cell which undergoes meiatic cell division to goren your haploid mogasporce. Out of this youre mogaspoke (totread) uppeок з тодазроне degenercantes, and the Lowell most megaspore (chalatal) becomes gunctional megasporte. The functional megasporce organices to gorem a gemete gametophyte ortis embryosac. *Types of Remale Gametophyие Mahesweuch classified embryosac or gemeere gametophyte into a types. ab Monosporric by Bisporric Petrasporic ay Monosportic It develops From the single megasporce of the sporce retread and other s degenerates. It is of two types 4 monospornic polygonum typeR 79 oenothera tyre 4% Monasporic polygonum type *It is & nuclecated embryosac discovered by strasburger. It develops from the cheelatal megasporce. It's nucleus divides thirice gorem 48 nucleus. They arrange themselves as 3 are chararal rends & act as antipodal cells. at mickoplie end forming egg appareaters & two occupies at the contree as polare nuciel. It is most common types of embriyosae. milosts mitosis AMA Egg apcrcatus polar Antipodal by Bisporic This type of embryo develops from one of the two dyads formed as a result of the first meiotic division of MMC. The other cell degenercates.. The one function dyad undergoes too mitotic divisions and forms & nucleus, which are arcrcanged as polygo -num type of monosporic embryosae It is of two types, ay Allium type: It develops from the the chouazal dyad by Endymion typeIt develops from the micropilen end. Peteasporic embryosас When melotic division of MMC is not ace- -umpied by cell wall formation. All the youre haploid nucleus lies in a single cell called coenomegasporce. All this parcticipate in the formation of eтькyosac called tetrasporcic embryosae. The nucleus arrange themselves & following types.